1. It sucks point blank. What most people don't know is that most every comedian you see is part-time. And the reason they are doing comedy part-time is because it's virtually impossible to do it full-time financially.
Long-Term, Hard to get going
2. So there are actually steps to being a comedian. It's a lot like being an office monkey for 2 years, then being a senior office monkey for 3, year, etc, you get the point.
What actually happens is when you first start out you either go in the middle or open for someone else and you are given approximately 3 minutes of time. Yep, that's it. Oh, you're not paid for this either.
Then after someone realizes that your shit is funny you get moved to what is the called the showcase. Ok, we're not talking the improv here, we're talking about some comedy club you've never heard of in a city like Tracy. For those in the Bay Area Tracy is in the middle of nowhere. In a showcase you are not the main act but are given about 5-7 minutes of stage time. That's actually not bad. Oh, did I mention you get paid nothing for this, the most I've ever gotten was a free dinner.
The third step, and really final "I've made it status" is doing shows on the road or at consistent venues. You'll be the main act and get approximately $200-400 a night and have about 10-15 minutes of actual material. I mean you're not Chris Rock but you're not a bum either.
People don't laugh at your jokes
3. This is the worst of all things about this job. Worse even than heckling (which happens more than you think), because this means your audience doesn't even care.