YANBentirelyU.
My sister and BIL are 'lucky' and hard working, they've received help that I'd have accepted had I been them, they're careful with money and they seem to be well set up. For me, it's not about their 'riches' because they're not rich, rather their opportunities that have enabled them to have long term plans, which I lack.
Does it affect my relationship with my sister? I refuse to let it. It actually takes an effort not to compare yourself to others sometimes, but I will always put that effort in.
My children are happy, healthy, wonderful company, funny, well fed, and they lack for none of the basics, the important stuff.
Yes I/we are always striving to give them more of the important things, we want to be able to comfortably afford every school trip, or out of school club, but these are extras, I never had them and I look back on my childhood with great memories. We have a lot of family time, we have fun. All the things that a mastercard cannot provide, we have, the rest is extra, and not all extras are good, and a lot of extras often require a sacrifice of some really good things.
You have to be confident that you are doing your best for your children, rather than providing everything they could ever dream of... very few people can match that.
My best friend as a child was piss poor. I ENVIED her, the closeness to her family, the time they spent together while my (lovely folks) worked every hour to provide bigger, better, more.
Don't let it affect your relationships, be proud of everything you achieve, be the best parent you can be. It's all you can do without becoming a misery.