I think you actually have to hate gambling to be good at it. You need to walk away from losses and not chase them. Be happy with a profit no matter how small. And you also need to be methodical and stick to your system.
Matched betting is different. That is just taking the free cash bookies offer and turning it into profit. Exploiting casinos is using mathmatical formula to exploit the RTP %s the casinos have to adhere to.
The problem for normal gamblers who use slot machines is that the slot machine is psychologically designed to make you take risks. Nice graphics, random free spins, wilds, bonus rounds, features to collect, random big wins. You need to be able to ignore all that, to focus on the maths and use the RTP against the slot machine.
You will have some losses but you need a bank that can absorb those losses. And they aren't real losses because eventually you will hit a big win of several hundred pounds which will completely negate the 10 £10 losses you had the day before. You aren't chasing wins, you are working the law of averages and the RTP% with the bonus offers.
You can manipulate it slightly more in your favour by playing at the right times. All slots have cycles of collect, break even, pay out. If you are playing on a pay out cycle you will make a profit.
Am not saying anymore now because casinos look for these kinds of threads. But it is possible and profitable to make money. Being a professional gambler isn't a new thing. And these days if you know how to use the exchanges you can be the bookie from your living room and make money on people losing bets.
Matched betting is pretty basic. I have done it and the amount of time it takes, and the amount of money I have tied up for x number of days while I faff around sending ID in isn't worth it. But manipulating the casinos I can see me doing. Am lucky that I know people who do and will show me how.
But don't expect someone on an AMA on mn to share knowledge they have built up over 3 years. All the information I have posted is available on various forums online. But you won't find people sharing their secret methods online for free.