Because life itself is designed to make you deserve the things you want. It forces you to sacrifice things to the point where you can actually can enjoy the thing you wanted. Life is not biased, the people living in the same world as you are and they are the ones who really make you go through hell the most. Oh you think I'm wrong? Here are some key points to really convince you:

If you think that life is responsible for the fact that you're lonely, check yourself out a bit. "What are you wearing?", "How do you act?", "Have you taken a shower recently?" are all questions that you need to ask yourself before even attempting to cry about being disliked by the people around you. Even your fake online persona matters. Don't just go around begging for attention, earn it. Deserve it. Make everyone else around you want to be with you. Optimize yourself and your habits. Start reading books or something like that and grow character. Then see if people dislike you or not. Of course you can't convince anyone into liking you, some people are just ignorant but they don't matter. It's your life and you should live it with the people that like you for not who you are right now, but for the person who dedicated themselves into becoming what you are.

Have you ever felt like the punishments you've received before have been too harsh? Maybe softer? The way your choices work aren't based on what you've done but rather where you've done it.
When or how you get punished in life isn't depicted by the thing you made, but by the things around you. Whether it's a tree that almost fell on you while walking in the forests in a thunderstorm or getting your paycheck lowered/demoted from your position for being an inconsistent employee, it really depends on the environment where you are. Don't just blame it on life like "Gagh! My life sucks! A random stray dog bit me on the street!" but instead wonder why you were walking alone in the middle of the night after drinking with friends. Maybe then you would probably be able to understand how things went south. Always remember to hold responsibility for the actions you take and where you're taking them. Risks you take are risks you make yourself.

One day, you'll be your father's age, and then your grandfather's age. And when you sit on your deathbed, what memories will you see in a flash? If you've spent your time right, you might see yourself doing your favorite hobby, or maybe that time where you almost got fired from work because of your printer failure. Those adrenaline filled moments in life are the ones spent the best. The ones that you've spent with the people you love or the thing you enjoy doing are the ones you must feel confident about. Life is short. And so is time. Don't let other people hold you back from what you want.

Are you still hating life? Do you still think it's all pointless? Have you changed your opinion on the choices you've made? Don't bother asking, just look at you. Where you are, what you've accomplished! Appreciate what you have and earned. You may not be a multi-millionaire, but you've changed yourself to a point where you're happy. You don't need to blame life for the things that happen to you because you don't have to. You know why things unravel the way they do.