Among other things, a commitment to "live forever" is a statement about acceptable risk tolerance. Ever wanted to climb mountains? Take up skydiving? Drink too much sometimes? Eat foods that are bad for you? If your goal really is to live forever, the risk profile of doing anything that doesn't minimize the expected value of the long-term risk to your person is probably unacceptable.

You personally might rather live a vastly extended span than spend the time you do have skydiving, parasailing, climbing mountains, and doing whatever it is that allows you to enjoy your life to its fullest for however long you have. But that's a real, legitimate choice, and choosing to take risks and experience everything you can is a perfectly valid choice -- even if there's a very real risk that something will go wrong at some point and you will indeed "die screaming."