The lead comes in already annoyed. He filled one form and four companies rang him inside an hour, so by the time you speak he is defensive, price-shopping, and treating you as interchangeable with a door knocker who quoted numbers nobody can hit. You paid for that conversation.
What makes it worse is that you know the alternative works. The homeowners who find you themselves, after reading something you published, arrive completely differently. They already trust you a bit. They ask better questions. They close at a better margin. You just have never had a way to produce that reading material at any useful rate.
So the marketing budget goes back into the lead reseller, because it is the only thing that produces anything this month. The cost per lead goes up next quarter, as it always does, and you are renting attention from a company whose actual customer is the homeowner, not you.
And if the lead source changes its pricing or turns off tomorrow, you have nothing of your own to fall back on. Nothing you built. Nothing that keeps working when you stop paying.