Is living without health insurance risky behavior?

I’m 50 years old with a pre-existing condition that might make it expensive to get new coverage later. Any experiences to share? I’d like to take that money and invest it elsewhere for a couple of years. I have no current medical problems and haven’t needed any treatment for over a year. Before that? Never. (My current employer will pay 1/3rd of the cost of my premium and the balance will come out of paycheck prior to being taxed. Would it be russian-roulettish to cancel my policy short-term?