Help I don't "own" most of my Bitcoin

So basically I have been investing in crypto most heavily Bitcoin for several months now. However it isn't until recently that I started buying via coin base so I can transfer it to my actual hard wallet.

I have a majority in webull and Robinhood. Both in red due to last 2 months. Which I was fine with since I was holding long term anyways.

But frankly my plan was just till wait till it was green and start slowly selling so I can rebuy on the exchange and have in my wallet. If btc is worth 80K. Doesn't matter to me if have to "rebuy" over at coinbase at that rate. Since I'll just be transfer funds locations.

The hard part is with the current price point I would hate to sell. And then have it go up on me while I bring the cash over to rebuy in.

Has anyone else faced this issue? What's a good approach to reduce that lapse time.

The money I have to invest I have been putting into btc on coinbase pro. But most of the money I have invested is on the other platforms... Which technically you don't own any actual crypto.

Thoughts?

I guess my plan right now be to continue to invest in what I can over on coinbase. And then eventually when my Robin Hood is back in the green just sell it incrementally and move funds to coinbase/ hard wallet over time?