I think it's a great idea! I've been earning full-time online for several years, and I've found that it's a great way to build my skillset and network.
I began blogging solely as a hobby. It was fun and easy, so I kept doing it. Eventually, my blog started getting more popular, which led to me getting more opportunities: writing for other blogs and websites, speaking at conferences and events, doing workshops on topics related to my blog content (like SEO), etc. And then when those opportunities dried up (which is bound to happen eventually), I had built up enough skill in writing that I could find other ways to earn money online—like freelance writing gigs or creating courses for online learning platforms like Udemy or Skillshare.
Nowadays, earning money online isn't really something that happens in isolation: you're usually building relationships with other people who are also earning money this way—whether they're bloggers or authors or speakers, or teachers themselves—and you can connect with them through social media platforms like Twitter or Instagram, where they'll share their advice on how they got started and what they're working on right now.