If you don't understand monogamy and find having a meaningful, long-term relationship to be absolutely pointless then that's perfectly fine, and you have the right to think that. That being said I believe that it's a healthy choice to stay faithful because you are demonstrating that you have the capability to show respect, loyalty and love to a person other than yourself, whilst also upholding your own principles and your own sense of commitment.
I was able to understand this more when I grew older and realised the difference between infatuation based upon physical attraction alone, and love, usually in it's blossoming stages after a certain period of time, effort and commitment from both parties, where you are able to be wholly self-less and caring of something other than yourself. It may not be for everyone, and if you are personally struggling with the concept and believe that you have the potential to cheat, maybe it would be best to consider open relationships rather than committed relationships for now.
On a personal note, I doubt that I would ever be truly satisfied being in open relationships and having one night stands all of my life, because I find it to be a pretty meaningless and soulless existence. I gain so much self-worth and happiness from being committed to another person, and I understand that for some people that might not be the case and that there are other sources of happiness out there, but that's what I prefer.