This is absolutely false.
For credentials, I have worked for several years in the industry testing slot machine software.
One of the things we test for is ensuring the game always pays out at the correct payback rate, which is always skewed so that the house wins. In most jurisdictions, the laws are written such that it is illegal to have a slot machine that pays back in the players favor over time (doing this would reduce the governments taxes).
In a sufficiently large population, over a finite period of time, there can be a small set of people that look like they are winners. This is called survivorship bias. Given enough time, these people will eventually lose.
However, anyone saying they know how to win on slot machines is probably just lying.
The house always wins in the end. The only way to win as a player is to cheat.
There are slots plays for advantage players ... when the jackpot reaches some amount there can be an edge for the player, they do promotions that can be gamed ... takes a lot of studying the minutiae for a loophole ... a more general article on advantage players https://www.nytimes.com/2016/07/03/magazine/how-advantage-pl...
You are absolutely wrong, but your comment did manage to get mine to -1 point, so thanks for that. You are correct that slots are as random as the RNG within them (which, as it turns out, isn't actually that random [2]), however that does not mean they cannot be beaten. Slots can be beaten in a variety of ways:
1) Any progressive jackpot that gets high enough can skew the game's return to players to above 100%. Believe it or not, digital slot reels can be mapped out and the return extrapolated (example here [1]). On a progressive slot, with this data and the meter rise in hand (which can usually be easily calculated through mere observation), you can calculate the level at which the progressive makes the game positive.
2) Various slot promotions can be beaten. For example, there was a casino team that was tipped off to a promotion where a casino in the midwest was, for 12 hours, offering a double payout any W-2G win (any win over $1200 on a machine). So, they went and played a $100 slot machine, where almost any payout was over $1200 - essentially getting a double payout on every win. They had an enormous advantage with this promotion. These kinds of mathematically challenged promotions are not as rare as you would think.
3) Many slot machines have a "must hit by" feature, where the progressive must hit when it reaches a certain amount. Advantage players wait for these to get to within cents of the payout, locking up machines hours before and playing the minimum amount very slowly, so that they are in a position to win them.
4) Some casinos give loss rebates to some players that can turn almost any game positive, especially when combined with techniques that I won't mention here. This isn't necessarily limited to ultra high-rollers either - I am familiar with a few casinos where significant loss rebates start at losses of just $1,000.
There are more.
So you are absolutely wrong that there are not advantage slot players. There are teams of them that work in Vegas and other jurisdictions.
Some games can get large enough jackpots to make a game +EV.
Doesn't mean the house would lose.
The advantage players would fight for the machine(s, if a pooled jackpot) and play until the jackpot was hit, at which point it would become -EV again and they would stop.
These machines are relatively uncommon, and getting more uncommon.
You can read about these players, I think they can squeak by making about minimum wage or thereabouts.
I believe most of these 'professional' slot players operate around the multi-machine jackpots which can sometimes get large enough to offer a positive EV on the games. They work in teams though admittedly is been a long time since I've read about it. There was also another guy I read about who worked on finding flaws in the prngs and pay tables but those would only last a matter of months before corrected.
My brother used to work in a bar and asserts the following:
Some days he would work all day and see people put money in a machine and not win anything much (e.g. jackpot never came up). Believing that the machine had a payback rate that would balance out over a few hours/days, he would deliberately put a bit of money in at the end of the 'no winner days', and would often win enough that it made it worthwhile overall.
Anecdotal, but it seems consistent with your understanding and is a source of an edge.
In the US & AU, I know they use a Theoretical Hold Worksheet which pre-specifies the win/lose ratios and is required for every machine. That worksheet doesn't make use of past wins/loses, i.e. it is stateless. This matches what you say.
However, I do not know what the situation is in the UK/EU at present, and I do not know what it was 20 years ago (when my brother was working there).
In the UK, it's common for gambling machines in places like pubs to have "compensated" payout odds that are are dependent on the history of wins/losses. Odd quirk of our regulations.
In a sufficiently large population, over a finite period of time, there can be a small set of people that look like they are winners. This is called survivorship bias. Given enough time, these people will eventually lose.
However, anyone saying they know how to win on slot machines is probably just lying.
The house always wins in the end. The only way to win as a player is to cheat.