Honest answer from a company that sells leads: sometimes no. Whether buying leads makes you money comes down to your follow-up speed, your niche, and which provider you pick.
If they cannot say in writing that a lead is sold once and never resold, assume it is not.
No SMS or phone verification means you are buying form-fills, some of which were never real.
Long commitments transfer all the performance risk to you. Pay-per-lead keeps the provider honest every batch.
Ask where the leads come from and what the contact rate is. Dodged questions are answers.