... without a break?
Is there a risk for bad cholesterol levels?
Yes, there's a risk...how sever? Depends on the person. When I'm on my "good" cholesterol is typically a little lower than it needs to be. It's not drastic, but the number can get a little low.
What's the biggest problem when you stay on for years and years? It's hard to say, I do think it's very individualistic, however, I also think everyone, no matter who you are does need periods of time off...the body needs time to regulate itself. Never allowing this to happen could cause some problems down the road, because I don't care who you are...I know there are tons of people out there who say they'll stay on for life, but come on, no one is going to run hard cycles when they're in their 60's and 70's. TRT? Maybe, but that's a completely different thing altogether.