Arguing that "disinformation is not a real problem, there's only ideas" is reductionism, like arguing that there's no such a thing as a forest, only trees. And a "battle of ideas" can definitely favor the side with more money - if that weren't the case, then why do politicians spend millions trying to outspend their opponents?

There are most certainly groups of people spreading objectively false statements, not as "disagreement" (although that exists too) but because they expect to profit from it. Is it easy to detect? No. Does that mean we should give up? I'd also say no.