21 bitcoins is 10k. I would use half of it for altcoins and use the rest of those coin for retirement. Just holdind my coins year in, year out so someday it is high enough and I can retire. Be it bitcoin or altcoins but with crypto money I will some day retire.
It's agood strategy, but knowing what to do in the altcoin market is key and right now I don't know where to put the bitcoins at. So many altcoins and so many scams, and the coins with teh big marketcaps seems to be stagnating now for a while. Bitcoin is going up tho.