Does it make sense to buy more at a time when the value of Bitcoin is increasing?
From an ideal sense or rational thinking, buying Bitcoin when the price is increasing does not make any sense. If you choose to buy when the price increases, then what are you busy doing when the price is decreasing?. This is probably a question you should ask someone who indulges in such act that the Bitcoin community call fomo.
But from an investment point of view, it's ideal to buy Bitcoin at every giving opportunity (whether Bitcoin price is increasing or decreasing). When you do this act a regular interval, with a specific amount, then we call it a DCA strategy. It's just a strategy that gives opportunity especially to those that can't make large purchase, so instead they do it often whether the price is increasing or decreasing.
The DCA strategy isn't bad at all, but when an investor choose to only buy when the price of Bitcoin is increasing, then I don't think that's a rational thing to do