Even if you want to own zero bitcoin, since they are lending in the crypto world, they can award higher interest. So, you can get 8.6% interest for cash deposits, pays out monthly. They offer 6% interest on bitcoin too(!!). If you wanted to hold your liquid cash before purchasing excavating equipment or something, and don't want to risk fluctuations in the stock market for example, this could be a good option.
The issue with Blockfi is you are required to put it in for terms, minimum of 6 months. Most defi projects let you lend stable coins on a flexible term; and plenty with rates around 12%. I got about 4.5% in a month on Binance, i.e. nearly 50% a year on the first month, but think it's down now. Nexo has 10% with no term, 12% if you get paid out in their token, which is worth more than fiat IMO. Youhodler is 12%. Fulcrum has a very stable defi rate of about 12-13%, so does Yearn.