Concerning the stimulus checks that some get, wouldn't it be better to offer investment money?

I know this must be irrelavent since I’ve never heard of it but in me but what if instead of distributing free money the gov’t gave out matching funds for investment. For example an average family invests $300 then it is matched with $300. It would have a cap so high income people wouldn’t become a super investor. The macro economics is fuzzy to me, including all economics honestly. What are the holes in this?