@Cheetah71 The highest paying path (i am referring only to being a regular salaried employee) would be breaking into Private Equity or Hedge Funds straight out of college, or doing investment banking and then transitioning to PE/HF.
Breaking into PE or HF straight out of college is extremely difficult to do, only the very tippy top students at Harvard and Penn (mainly Wharton or dual degrees people) have a decent chance to do that since most top PE/HF companies recruit almost exclusively in these two schools and only a handful of the very top kids get selected.
No you do not need a Phd, unless you want to conduct scientific rehear for a major pharm, chemical company.
But I feel you should be thinking about what you enjoy doing not what job will enable you to make the most money.
@Cheetah71 you can do PE and focus on the technology or pharma/biotech or chemicals industries. You would bt doing actual scientific work however, like in a lab, but your scientific knowledge will help you in these business roles.
But if you want to actually work in a science role then go ahead and do that. You could maybe do that at first and then go into business.