Take advantage of the Bitcoin halving and make a small profit
No doubt, those who can should make sure they have bought enough Bitcoin so that they can get as much profit as possible once the second phase of the bull run starts in which we don't know how far the price of Bitcoin might go. Though the price of Bitcoin is quite low at the moment, it isn't the best price for buying but since we don't know whether the price will go any lower or not, investors need to start doing DCA from this point to make sure they don't miss this price point.
Since you didn't mention anything in the OP about it, I assume you mean altcoins by junk coins and even though you are right that one shouldn't hold a lot of altcoins, I don't agree that all altcoins are junk but a lot of them can be very profitable during the bull run alongside Bitcoin.
Yeah no doubt for pointing about something to invest directly on bitcoin since its no brainer after all that bitcoin is really the best investment we can get. But the problem is the execution and thinking about for short term then get small profit since any corrections might affect our decision so instead that we can earn we might lose our money especially if we don't know how to handle well our bitcoins since the only thing we expect is to earn about bitcoin. Risk management is important before we can achieve that.
Maybe OP is 100% into bitcoins and nothing wrong with this but I also doesn't agree that all altcoins is a junk since there are a lot of them performing good. Its our choice if we want to choose multiple investment and don't focus only on bitcoin since there are people believe on something that they need to split up their funds on multiple investment so that they can get a possible good result.