Over 27 years I have worked at 8 companies. 6 were large to medium size publicly traded companies and 2 were startups.
The startups were very chaotic and when I saw them fail to sell the companies 5 times, fail to secure more funding, layoff employees, no raises, no bonuses, failure to listen to employees, I could go on and on...
My explanation if someone asks is that I thought they were good opportunities but I was concerned about my job security after all of the issues and more I listed above.