Theres never any 100% profitable strategy in staking. It all depends on how much you want to make. If you have 1B and want to make profit through martingale, of course you might, as the chance of losing is so low, but you won't understand how much of a bad idea it is, until you actually do lose everything doing it. So saying that you have profited in the past from it, sure, you may profit another 5 times in the future, but the 1 time you get unlucky and lose, you will lose all your profits+everything else you have. You can't keep winning. Ive seen 15x win streaks, as I have seen 15x loss streaks before.
Owning a staking clan, I see many people get cleaned via martingale daily, as I see many making good profit with it. You need to know the risks.
Staking is the same no matter what, if you have 1B, and want to make 1B profit so you have a total of 2B, the fastest way is to just do a 1B stake, 50% chance to win and lose. No matter what you do, or what approach you take - the chance you turn 1B->2B will be the same.
It is gambling at the end of the day, it can be much faster money than anything else, but you can also lose everything, and that is what you need to understand. There is no method to it, there is nothing more to it than that. If you chose to gamble, you accept the risks, hence it should only be done for fun.