Why use Dtube or any YouTube alternative? YouTube is the largest website for user-created content. But YouTube is not perfect, and some people want alternatives.
Recently YouTube has made earning money from ads much harder. YouTube has been demonetizing videos and enforcing a much stricter ad policy. As this article from the Verge points out this is causing much frustration.
The fact is on YouTube unless you have other revenue streams if you earn from ads you are at the mercy of Google. Advertisers are cracking down, and some are leaving YouTube.
It also doesn't help in recent two cases high profile YouTubers have caused huge controversy. Felix Kjellberg (PewDiePie) and Logan Paul. It is no secret that YouTube is losing Google money.
Google is getting much more strict with who can earn money from ads.