50 dollars monthly is not that bad specially if you know which coin you are investing (this means altcoin of course) but if you are confident about Bitcoin to bring you better result for that amount then yeah put that 50 bucks in bitcoin monthly and that would be 600$ a year, that for me is too small talking about how pricey bitcoin nowadays.
but this is for OP to decide, he has His strategy and we are just giving Him second option and better understanding about things in life.
It is still very possible for $50 to be used for Bitcoin even if you say that Bitcoin is no longer at a cheaper price. However, this is still very meaningful for anyone who wants to put their money into Bitcoin with the aim of making a profit every year after putting their money into Bitcoin every month. And from the first option you mentioned, it seems like a very, very bad choice in my opinion and is really more risky, especially if you choose a new altcoin whose market trend itself is still not guaranteed for the long term.
Meanwhile, for an option like Bitcoin, with an amount of $50 every month, it would be a very extraordinary thing if the OP could diligently and happily put it into Bitcoin. And it should be for everyone to make the choice of Bitcoin their main choice after seeing the increase and improvement in prices that have continued since last year until now, supported by several positive effects for Bitcoin itself. In fact, everyone will not know what the condition of their money is when they put that money into altcoins, some of which are shitcoins.