This article is based on my exp in staying and working in start-up as well as in USA.
1. You like to work on innovative things. I am not saying innovation would not happen big services and product firms. But your motivation to work is more.
2. You have risk and reward model in earning or growth. Some times they sink. You will be on the road, it is better to have safe investments or savings to cover your day today expenses of your insurance, kids schools, living expenses.
3. You have freedom of selection of tools and you have dedicated team help at your disposal. Not to mention UN ending approvals , explanations to the senior management in big firms.
4. You can become rich if the company’s products are hit. Read Google, Facebook and other firms.
5. You have great team to guide in particular skills. I heard in some big firms, you will end of workingon small code base, in trillion lines of code.
6. You can prove your leadership skills and build fantastic team. In one of American startup,, they have assigned me to take care of whole os porting.
7. You will have greater learning curve, as you will be working state-of-the art stuff.
8. As team will very small initially, you will have greater bonding and cooperation. 9.your potential is streched to limits.
10. You will only have two choices like war (do or die) .