Is blogging a waste of time?

I've been blogging now for more than a year and a half, and sometimes I've wondered if blogging is a waste of time. I have been very busy lately, and I haven't even had time to read the comments. What concerns me most is comments from people in my own family, who tell me that blogging is a waste of time. My father thinks I should be spending my time on a masters degree. My cute Iraqi friend in Boston told me that I should be doing something more productive than blogging. I know that I've learned a lot from my own blog and other blogs, but sometimes I also wonder if I could be doing something better with my time.