First of all, you can't question something you don't know,
or at least don't have experience with,
just because the friend told me "it story," you should try it yourself.
-/imo/-
When a player understands ROI, he can go for years with a return in the red, but stays close to Breakeven, which allows him to recover, or have a positive return.
The thing is that if you are an occasional, novice, recreational player, those phases do not matter to you, in fact you will never understand them, but that assumes the long term as a mark to know where they is ROI.
For example, last year sports betting left me at about 8mbtc in the red, in 2023 adding royalties, bonuses, and profits I am at +18 mbtc, so I am +10 mbtc.
In traditional games, things can be tougher, in my case the maximum bet size there is $1, but on average I am around $0.5/BTC, and just this year I am at 400x with a bet of $0.2, technically I'm at +8$.
It is rare that the long-term return does "scared" me, since the size of my bets represents 100:1 the bankroll allocated for betting on traditional casino games, and I make this same relationship for several casinos where I gambler.
In poker, I can be more risky, sometimes I play $20-$30-$50 tournaments, and there I can even show you the statistics by country, from the data collected from some "millions" of players.
Poker is a little more complicated to explain to you how returns are obtained even if you have bad months, but with proper bank management and knowledge of the game it can be easier to be on the path to exceeding your ROI=0.
Largest Live Poker Database - Poker Hendon Mob
https://www.thehendonmob.com