Champion league is best achievement for every club and give much income when participating on this event except Barcelona as historical club have many champion league trophies.
You are mixing two different things. Current income from current season and result in Champions League matches are different than past trophies. Barcelona won't earn any additional income from their past trophies in Champions League. I know that can sell tickets for visitors to visit their club, Hall of fame, etc. but such activities and income are seriously affected by the pandemic. It is also now what you talked about.
I think they have two way for participating in champion league next year, first should success finish on top four position standing in La Liga or try other way become the champion on Europe League if failed on La Liga standing top four position they still get chance for next years pass to champion league with Europe League way.
It is very risky to bet all in Europa League. Even if they bet it and focus all resources for Europa League, they might fail too. We already see in this season how easily Barcelona can be beaten by small and medium clubs. Since they are falling down in quality, opponents don't need to be Real Madrid, Bayern or top notch clubs to beat Barcelona.