Do I have to go to university to become successful?

No, you needn't to go to university to become successfull. There are many jobs and many opportunities to work as self employed which doesn't require university degree and you can be successfull in them. Furthermore, being successfull is relative and very broad term. You can be successfull in your career, family (having good spouse, well raised children), hobbies, sports. It is almost impossible to be equally successfull in all area of the life, it is why you need to find out in which area you wish to be successfull and then work on it. For many of these areas (family, sport, art, many careers) you needn't university degree and you needn't to go to university for it.

No, you don’t have to go to University to become successful. There are many options for higher education or work experience after finishing secondary school, sixth form or college. Some people choose to go on a gap year to gain some work experience in different work environments, others join apprenticeship schemes, and some do higher education courses - which doesn’t have to be at University, you can take online courses instead. So there are many different routes you can take to become successful, it all just depends on how much effort and work you put in to your career path.