Spending 5k a day on feeding is unnecessary for someone trying to do something for himself. What he should be on is management, which if he doesn't will end up saving or investing nothing at the end of the month after pay.

If you seek advice for your friend, do not advice him to invest in Bitcoin now, according to your explanation he barely has enough left and even if he saves what he ends up with for a year, it won't come up to significant figure, he can do mini trades in Naira then from there initiate the profits inside Bitcoin. Once the business grows that means his investment grows along.