I actually have no idea why BTC tanked around $1000 today.

In the past there was usually some reason like hacked exchange or ETF rejection/delay or China ban.

After research I can only come up with 2 reasons. First one was some over leveraged longs on OKEx, basically similiar to what happened a few months ago with that half a billion liquidated position.

Second one is Craig Wright saying he really is Satoshi and he will sell all his BTC to fund miners to mine SV instead of ABC and SV.

I think the former makes more sense to me.