Though the Reds have signed two youngsters, they are yet to make a marquee signing compared to Manchester City, who have broken their transfer record to sign Rodri from Atletico Madrid.
But the German trainer believes the right time for the club to also spend big will come and is not envious about the activeness of his competitors.
"I can't say anything about what other teams are doing. I don't know how they do it. We have to pay bills. Sorry, everybody has to pay bills, we have to pay bills," he told UK newspapers.
"We invested money in this team. Now it looks like we are not, but we are not in this fantasy land where you just get whatever you want. You cannot do it constantly.
"It looks like there are four clubs in the world who can do it constantly – [Real] Madrid, Barcelona, City and PSG. Whatever they need, they do. You cannot compare that. That is the situation.
"It is not a criticism. I know how people will take it, that I am jealous or whatever. I am not at all jealous.
"This year is not the end of Liverpool FC. Next year there will be another transfer window," he said.
"This team is really good and we have invested a lot in it. Now we have to work with that."
