Promos Always Feel so Frustrating

So at the start of this season I was placed in bronze and got into silver relatively quickly given how often I play ranked games. I got through S5 in a few days then got through S4, but by the time I got to S3 I kept getting demoted immediately after promos. About 6 or so times. Usually streaking back through placements but then getting immediately demoted again. A few times I dipped as my MMR was low but I kept repeating this. Recently I got into S3 and got into S2 in a couple days. But then got immediately demoted again and have since streaked back into S2 and am again in a losing streak immediately after placing.

I know the system tries to maintain a 50% winrate, but why does it feel like a punishment to have a winstreak for promos? I win enough games to gain back 100 LP and then enough to get the win in promos. But if I win a game in the new division and lose 2 or 3 games, I get demoted and have to repeat this process. I've come to expect an afk or just a few bad games after a win streak, but it feels frustrating that this happens after promos when you're supposed to streak in promos. It feels worse when you actually win a game and then lose 2 games because you don't get the 0lp net.