I think something we all need to remember is that there will always be something new for us learn, but you don't have to learn it. I started programming in PHP about 10 years ago. At the time, people told me not to waste my time, it's a junk language that will good the wayside. Today? Still writing PHP, and getting paid alright to do so. I follow the industry and trends and I look into the latest and greatest and I'm aware of what's going on but I rarely spend any time learning it. As long as I know the pros and cons of X and what I would use it for I'm content.

TLDR: Don't worry or feel the need to know everything. Pick what you love and enjoy working in and focus on that.