The hardest thing about making money online is the tech. Either you try to wrangle it mostly yourself — which is extremely time-consuming, and full of hazards — or you hire people to handle tech for you — which is very expensive, and full of hazards.
As the Internet matures, there are more and more turnkey ways of setting up shop online, thanks to slick and polished services like Squarespace or Shopify. On the other hand, no service is perfect or covers all the bases, not even close, and you are always dependent on several of them, and the more control you cede to them the more you screwed you are when they don’t work. Even if they all ran smoothly all the time — ha ha ha! — any good business will inevitably have idiosyncratic needs that turnkey services cannot accomodate. And then you’re back to either figuring out how to do it yourself, or hiring someone to figure it out for you.
When I was much younger, the standard major caveats about starting a business were to make sure you had the stomach for it and (this is crazy, I know) an actual business plan — not just an beautiful idea and a fantasy about being your own boss. Still good advice, of course, but these days it’s eclipsed in any business heavily or wholly dependent on a website. The modern caveat for many kinds of business is now beware the tech.