Games r expensive

So one of my close friends got a game called DayZ its popular u probably know it. I want it T-T but so poor. I want things like 7 days to die also. all dem zombie horror games. so i was looking around on Steam and then noticed all the games cost so much lol. Well at least i have some games :D. Why the hell games over like 20 dollars kids cant afford dat much then again dayz isn't meant for kids...... lol.