If they had nothing else going for them then maybe they would have cared, but they do have the league title race going right now so they would probably care less. It would have been nice, but it just didn't happen. Think about it, we are talking about a potential 4 cup season, that would have been insane.
At the same time, now they have one title possibility as well, they already won one, so they will end with just one, but they may lose the league and europa too. So if they end up like that, then I would assume that they would be pretty upset about that without a doubt. I think it's clear that they will try their best on everything that is left, at least they could give it a shot and see how they will do eventually for sure.
Actually, the target of achieving four titles is quite reasonable because Liverpool is actually capable of doing that, but in reality they had to forget about that beautiful dream because they had to be eliminated very painfully by Manchester United. Now Liverpool are once again hoping for luck in the Premier League and Europa League, of course the two remaining trophies are prestigious enough to always be able to get. The opportunities for the Reds are quite open, it's just that Klopp must always be self-aware and use yesterday's defeat as a lesson. But what is clear is that it is not easy for anyone to win the EPL trophy.