Honestly it's pretty easy to screw up on it...with many people. Or even have a horrible view on it. Not every friendship is worth it...I'm definetly not saying that, since if that was the case, everyone would be friends with everyone or be used in a bad way or...well it's just not possible for everyone to be friends with each other in the 1st place, because a lot of people clash with each other or don't even care about others in the first place.
Some people just want to manipulate you or use you to gain information on other people. One of my ex-friends, well honestly don't think she even fit in the friends category, since all I wanted to do was help her, but all she did for me was like play the victim card with me or told me not to be friends with someone (all my give like no good reasoma, besides oh that person likes to create drama, but gave no examples or what not on how said person does). Basically she just bitched and complained about others, even sprouting numerous lies like she had 23 or 26 or 25 boyfriends (this was someone from highschool by the way). Or going around saying people she hated had dark auras to them when said people she claimed had these auras weren't bad at all, just weren't under her control or she just had huge jealously issues.
Anyways moving on from that disaster, spending time with someone you don't even consider a friend at all but other people do, isn't much better. Especially if person treated one of the people you cared about like crap, like dismissing feelings or rather hang out with someone else beside them. Then there is the case where someone doesn't want to tell you anything about themselves anymore, since they hate being talked about a bit even though it's pretty damaging for you to sit there and listen to all their emotional/mental problems and be expected to keep it to yourself,even though its breaking you inside and you need to vent to someone about your own problems about that.
Trust me, you can have friends that you barely talk to you during a year and you guys are fine talking to each other and nothing is wrong. Some friendships get screwed up by romantic feelings of course, especially if best friends at first then went out and then went back to being best friends,but still act like a couple. Yet never got back together and you had to let them go, considering they still had feelings for you but wasn't going to change or do anything about it so ended up making you feel like the whole friendship was pointless.
Then you got the one friend where you been through a lot,but had to end it in the end, since too much damage done, despite still caring and trying to mend it by appreciation, yet just seem worthless to bother, considering both were always going on different paths in life and clashed a lot, despite effort and too much stuff from others and each other for that matter ...some friendships weren't meant to last..some friendships weren't even friendships, but you just having a good heart and wanted to help someone so badly, since you understand so many people need someone and you love helping, but you felt drain from them, considering you got nothing in return.
It's rough...I know it is. So many things can break a friendship...but you know what so many things can make a friendship like someone making you laugh after they do something stupid or someone checking up on you, making sure you are okay and that you look fine. Or they tell you they appreciate you and your honestly or that you act like an anime or book character (in a good way). Or just glad that someone is always there, and when you hangout with them, you can just sit there and play games or watch anime, while talking about life or talking about how hot a video game character is.
Sure you can screw up friendships in a lot of ways….Not all of them will be permament damaging as long not constant nor major ones that break someone. But you can focus on making friendships better (well people you connected with on that level, since like I said can't be friends with everyone and I'm telling you can't force friendships either) by just doing little things and being yourself really. I mean I still have friends of course, so I'm not alone. And honestly screwed up on friendships, but I don't think they were meant to be in most cases…though one or two I do have regret/guilt for that I let go or it didn't work out, but can at least cherish memories I had with them.
Having friends is worth it...just need the right people and it takes times. Sometimes it might take years to realize a friend isn't worth it anymore...not always a bad thing, or that they were a bad friend or you were either, just pretty much ran it's course and you guys need to move on...but hey at least you still got your memories, the ones you can cherish and make you smile, even if you have ones that make you sad and angry, there will always be more memories to make with the true friendships you have or will get.