Money issues and conflict are difficulties found in most marital relationships at one point or another and it’s not sinful to acknowledge the pros and cons of any situation. I think the reason married people give you “the look” when you say that isn’t that they think you are selfish, but that they find those downsides to be superficial when compared to the many tremendous benefits of having a family. Sort of like saying, “I’m glad I didn’t win the 18 billion dollar lottery jackpot because you just have to pay taxes on it and who has time to write out all those cheques anyway?”
If you feel the need to apologize for your single life (and there’s really no reason for you to feel obligated to do so), you might get more understanding if you concentrated less on the superficial downsides you perceive about married life, and emphasize the exciting and important opportunities you have as a single person.