the martingale strategy really sucks, I'm better off using the flat betting strategy in all of my bets, I prioritize long-term profits rather than dreaming of big profits in a short time
That's a bit of a weird statement. Both strategies (flat bets and martingale) have exactly the same odds and in the long-run, your net result (profit or loss) should be exactly the same in both cases.
The only difference is psychological and depends on your discipline, e.g. in flat betting, it might be easier to stop and accept the loss.
It gets dangerous on martingale strategy, in flat betting you expect 99% return on your overall bets while doing the same strategy with Martingale means it accelerates the "bust" process with upcoming loss streaks.
I agree about the psychological or discipline side of the story but the main question is what kind of bankroll user has to manage expected loss streaks.
The difference is clear for experienced gamblers, anyways, I don't suggest applying aggressive double of the previous bet on each loss management even to my enemy tbh...