What would be the point of trying anything if you are going to quit the instant you failed in. You are bound to have a few failures before you get success in anything. Not to mention that this sort of program is actually beneficial to the world and it's people.
If we cancelled every program because of failure, we would rarely see success. Did NASA shut down after failed launches? No way! You can't move forward and learn from your mistakes if you throw in the towel after a failed mission. Learning and growth are based on failure, and the company must push on to get better.
Any new technology has problems. If every program that had things go wrong were cancelled we would never learn anything new. Besides, it is a privately funded company. The United States is a land of private enterprise and this should be no different. Cars crash everyday with people controlling them from behind the wheel and yet we still build new cars. I am sure Ford had his problems too, but where would we be if that was cancelled. SpaceX should be able to work on and continue to improve its technology. Someday we may all use space travel like we use cars.
If space programs and missions were cancelled every time they failed, we would not be at the level of knowledge about outer space as we are today. Many may find it useless to know about it, but we might be surprise at where this knowledge can take humanity when the Earth no longer has the conditions to house humankind.
No, SpaceX should not cancel their space programs. All space exploration comes with a certain degree of risk, and no advances in the field would be made without learning from risks and failures. SpaceX has had many promising successes that speak to the effectiveness, purpose and promise of the program.