The thing with Haalands worth to Dortmund is that objectively they do not have the quality in the squad for close to guaranteed CL qualification. And when you take Haaland outv of the mix, then they might individually not even be a top 4 team in Germany anymore. Potentially missing out on CL qualification is not just depreiving them off the 30m initial UEFA payment, but it also affects further price money, valuable sponsorship agreements, TV money and of course the quality of players Dortmund is able to attract on the market.
Dortmund is heavily dependent on making the CL each year, as missing out on that throws them multiple years back in their growth. And now they are already struggling WITH Haaland who is likely the only player that can still get them there, so it's hard to imagine them reaching it without him.