Hello. I see different platform like nexo, blockifi, etc... that can borrow you crypto or stablecoin. I'm here to ask if you have a strategy for example you borrow btc with an interest rate of 6% and then you use it on defi with 8% APR. Thanks for helpful. 
Borrowing to invest in crypto is worst thing that you can do. You can get hacked and lose everything. But you will still have debt to repay. A lot things can happen then just coin price goes up or down. It is way to risky, please stay out of it.
and it will be a burden in your life that has fatal consequences if your plans do not match expectations, you have to stay away from it and if you want to invest it is better to sacrifice what you have to sell and for capital gradually.