Dead serious this is how:
First, I don’t know if you can get to 500 SR if you are playing by the rules. That’s actually hard, you have to be really, really bad.
But you’re just going to naturally drop SR while trying to win if you take characters that are off meta. Now, a smart team can build around that, and tough on you if they do. Then everyone deserves the win. You’ll also win if you’re good enough to, so there’s that.
Otherwise, the lack of balance in Blizzard’s selection of characters will carry you lower. This is different from ‘throw’ picks which are not a thing (they aren’t. Blizzard lets you choose any character, therefore any player accusing you of throwing just because you pick something is straight up lying and breaking the rules themselves).
It’s not about playing bad, it’s not about throwing. It’s trying to win, doing your best with the characters that are offered. It’s just that Blizzard has made some characters terrible in the game by comparison to others and that’s on them.
You try your best. Maybe you’ll be able to drop to the best rank in the game, maybe not. I’m stuck in silver right now, and I hope to be back in Bronze very soon.