You need to divide that into multiple investment you do not need to do all in in 1 or 2 coins, i agree that you need to have bitcoin and eth but much better to buy 5 or more altcoin that you know have potential to give you a profit to achieved your target income.
It's not that easy to tell which ones would give you profit and a lot of them now are starting to lose value as time pass by. If the time frame was only for a year or less it could be a viable option but in 2 years the top altcoins we see now might not be even up there anymore. With how most altcoins depends on the price of Bitcoin it's better(imo) if OP stick with the two instead of buying more.