It's profitable to just upgrade the drug production buildings (skip down to the largest one) and you recoup your steem in a few days. I did the highest 2 and expected payout is 3 steem for tomorrow. IMO the best use of steem is to pay to upgrade buildings focusing on drug production. Then use those drugs to increase your heist payout.

Being that you get paid for production of drugs and for the heist which takes drugs that is what you want to focus on.

I also upgraded so I can produce some defensive troops, but based on how often you are online that may or may not matter to you.