I would never invest that much money into alt coins xD it just sounds like too much money. But thats just me im very sceptical and wouldnt risk that much money. But hypothetically if I had a lot of money I would probably invest in blockchain gaming and DeFi. For example ENGN and AXIE look good for the blockchain gaming and ReFi for the Defi (i keep part of my ETH and BTC on ReFi they have some good rewards). I probably would go all in on one altcoin 
find a few projects that you like and that look good and stable.
find a few projects that you like and that look good and stable.I might also do the same as you because after all these three coins are the top coins of all and there is no doubt for sure,
both Bitcoin, Ethereum and BNB all three are also very viable and suitable for long term investment,
apart from that investment is not an easy thing it takes patience too