Most do.

Most of the good ones were personal channels that turned into businesses. This transition means that the incentives changed and the original plan is no longer valid.

Most of the good ones that stay good are ones that stay true to the original plan: businesses stay business like and focused and personal ones continue to be personal.

Popularity increases the monetization and this usually destroys good personal channels, because they are then forced to pay attention to numbers and deals, unless the creator specifically avoids pursuing that (ie, they are sitting on money, but refuse to touch it).

Then, once they start relying on the money, they have to do whatever they can to keep it coming. This usually means either shilling or repeating what was popular before until it gets old or destroyed.