If you're a long term holder or have a high cost basis, you should be worried about this. What's more worrying still is that the "users" that spiked the price last year were nothing more than speculators looking to get rich. Compared to the number of people buying bitcoin, the number of people actually using it is only a small fraction of that. Metcalfe's Law contemplates value related to legitimate utility, which speculators don't play much of a role in, if any. The spike we saw in 2017 was not sustainable and not legitimate use of the bitcoin as a currency or medium of exchange, which is where any value under Metcalfe's Law would come into play.
Honestly, it is actually becoming worrisome as it would get to a point where bitcoin will only become more of a speculative asset with the way the price is being manipulated either in spikes or downward trend, which would make it hard for anyone to even end up believing or coming to terms with the real life usage as a currency eventually and to me that does not make any sense as that real life usage will always help sustain its value in a way, otherwise we will just keep having a pump and dump market in our hands.