I used to dabble in learning web design when it was all about HTML and CSS was "the new thing." I felt really proud of knowing how to insert an image onto a web page. Then people started using Flash, ASP, and PHP, and XML, and I got overwhelmed. I knew I'd never be able to master it all, and I quit.
Now I'm at a really boring job all day and I need a mental challenge. There's a lot of good information out there, and while I may not get a thorough education in web development for free on the internet, I'm hoping to get enough practice to be less intimidated by it all. If it turns out I'm interested enough to keep up with it, there's no law against a midlife career change. If not, it's an inexpensive hobby.