I think I am pretty much the same in real life as I am on here. I don't think I am vile either here or in real life (except to myself - the only person I put down on a regular basis is myself - I am shit hot at that).
I try to be kind here, but will be stern if I think it is warranted. I try not to go over the line.
I do think that your experience of MN depends on what you are looking for. If you think it is full of mean, hard keyboard warriors, putting others down, that is what you will see. But if you look past that, you can see so much more here - people offering help, support, advice, information to people going through conception, pregnancy, birth, breast feeding, weaning, post natal depression, other mental health issues, special needs or disability, education, bereavement - the list goes on and on.
Look at the Woolly Hugs project - that started on MN, as a response to a poster whose 2-year-old son died of a brain tumour. We wanted to offer some comfort, but weren't sure how to do so, given that we are all over the country - indeed the world - until some bright person came up with the idea of knitting or crocheting squares which would be made into a blanket, to offer some physical comfort at such a difficult time.
That project grew from that one blanket into a huge undertaking. We still make blankets for MNers who lose a child or a spouse, or when the MNer is the one who dies, we make it for the family. We also make blankets that are given to children in hospitals, to women undergoing cancer treatment (in the name of IAmTheZombie - a much loved MNer), to children in Africa, to the children who come to the UK from Chernobyl each year, and even blankets to wrap premature stillborn babies, so they don't have to be wrapped in something impersonal like a hospital towel - nothing will take away from the pain the parents are suffering at that point, but seeing your child wrapped in a bit of towel might add to the pain, and Woolly Hugs helps to prevent that, for some parents. We also run online craft sales to raise money for a range of charities.
Then there are the MNers who do daft things or have ridiculous accidents, and have the generosity to come on MN and share them, so we can laugh with them. Look for the thread about the elderly Korean lady in a MNer's garden, or Mexican House Thief, or Brian from Hull offering yoni massages, or the sheer joy that was TantrumsAndBalloons looking after her friend's three year old - here.
There is a saying I vaguely remember - we are all in the gutter, but whether we see the muck or the stars depends on which way we look.