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.