I read 2% capital (account size) stop loss per trade is the "sweet spot" for most traders.
First, "capital" and "account-size" aren't necessarily the same thing (in fact, I'd suggest that they're
rarely the same thing).
Secondly, I'm guessing that the reason you see "most traders" saying that is that your source of information, from which you're forming that impression, is "traders chatting online" (i.e. websites, forums, Youtube, etc.) and I'd suggest that what you're actually looking at isn't meaningfully "most traders" at all: it's perhaps mostly a self-selected section of the enormous and frequently changing turnover of "people who aspire to be traders but aren't really", including those attracted by the potential outcome rather than by the process.
Thirdly, I think 2% is an
enormously high figure, and pretty misleading, and I'd venture to suggest that the great majority of people exposing as much as 2% of their capital to risk on any one individual trade (who don't change their ways) won't still be trading 5 years later: it will - for most of them - be "something they tried to do in the past" before deciding that "trading doesn't work and it's all a scam, anyway".
Fourthly, I think that people trading successfully, over the long-term, with that sort of position-sizing are probably, overall, much closer to what I'd call "investors" than "traders".
Fifthly, it depends on exactly how you define the terms and how you work it out: I know of people who trade
stocks who consider their "position-size" to be the proportion of their account-funds that they put into one stock (rather than the proportion of their account exposed to risk in the trade - which can be something very different, if they have a stop-loss) ... I'm not saying they're "wrong", but they're certainly using language differently from most other traders I know, and the terminology is ripe for confusion, anyway.
In my misspent youth, when I first started off trading - like quite a few people, I started off uneducated and undercapitalized, trading spot forex against counterparty "brokers" using grotesquely high leverage, ridiculous position-sizing (though never as high as 2% of my account - 1% was my absolute maximum for my rare, highest-probability, highest-win-rate trades), I was full of unreasonable expectations and (briefly) thought that 2% was perfectly sensible for people who wanted to risk that much.
So the highest stop-loss I've ever used, myself, represented position-sizing of 1%, and that rarely and only at the start, and that was 1% of account-size, not 1% of capital ... and it was too high (though I did actually get away with it).
People who survive for the long term tend, overall, significantly to reduce their risk-exposure per trade as their accounts grow.
People who look at trading in terms of "
how much you can make" use bigger position-sizes than people who look at it in terms of "
drawdown-avoidance and risk-management". The former group doesn't survive for the long term; some of the latter group does.