Suppose you earned 60
BTC by working hard for 5 years and one day you decide now you don't want to work then what would you do with that amount?
How would you invest that amount? What will you do? Hold it dreaming the price will rise? Sell it and invest the fiat? or start a business? or retire? Any ideas?

having BTC is already a investing so what do you mean by INVES?
but since that's a big amount i think you can convert the 30 BTC to Fiat and invest in business that you love to do,since 30btc i already a huge amount that can give you good business if you can manage rightfully .
and the 30btc that remains in your wallet can be divided into 2 equal parts the 15bitcoin will serve as long term investment,can be 1-5 years or 6-10 depend on your desire holding,and the another 15 will diversify to 5 ranked coins next to bitcoin for semi long term or atleast 1 year holding.