To sustain an online cup system people actually need to sign up for them. However, it is ingrained in people's mind that ETF2L is the prime place for playing TF2, so people only play online cups if they are done on ETF2L. However, if you look at it objectively, ETF2L is a really shitty system compared to online cups. If you play well for 8 weeks and focus hard, you might win prem, which will win you a whopping €500, which is half of the prize you get from winning ONE qualifier. You can not fund LAN trips from playing ETF2L alone, that's why people need to support online cups so they keep happening, and so people can actually fund themselves to LAN without having to beg the community for a fundraiser every single year.
People from all divisions, please stop prioritising ETF2L above online cups, the priority is the other way around if you want TF2 to keep living. There is a reason why SUAVE/Serpents play in these cups and not in the season. There are 200 teams in ETF2L, if just a a fifth played in online cups we would have a MUCH healthier online scene.