It is more a result of a diversification of revenue streams. The online advertising market can be variable. Some creators have been extremely successful in building their entire business based on the advertising. This often happens with what we call brand-appropriate or brand-safe content. If you're creating very family-friendly content, that can be very attractive to advertising. It can be lucrative. If your primary market is one that advertisers want to reach, that can be very lucrative.
In other instances, they will want to diversify their revenue streams to supplement that advertising revenue with brand deals, sponsorship deals, crowdfunding and so on.
Again, you'll often see a fairly different revenue mix depending on the nature of the creator and how they do things. To be honest, musicians would be no strangers to this, because they are used to diversifying revenue with live events, performances, merchandise and so forth. The same basic rules apply across all classes of creators.