That way you're just only thinking of yourself and not about the ones that surround you. You may be strong and healthy and have an extremely low risk of severe cases, but what about the others? Being young doesn't make you less susceptible to the vaccine, it only helps you to come through this illness easily. But without a vaccine, you may get infected and the virus will replicate actively inside your body, making you a living waking source of the infection. Thus, putting everyone who's around you at risk.