Gym accidents - Asking for a spot

I'm curious as to how many of you don't ask for a spot when you know you should.

On Friday I was training and I saw a kid benching with something like 295lbs on the bar and it was sitting on his chest. I ran over to lift it off of him and he had already decided to dump the weight but it wouldn't come off because he put collars on the bar. I took the collar off one side and started to slide the weights off and the bar shot up and missed hitting me in the face by no more than an inch! I was so pissed at this kid because he didn't ask for a spot and pissed at myself for almost getting hit with the bar.

Why don't people ask for a spot?

For bench press type of movement I only use dumbells so I dont really need a spot.

Maybe they think that they could handle it

I always get a spot when benching heavy. One time I asked some guy if he needed a spot because he had a lot of weight on the bar. he said no...3 minutes later I hear the weights come crashing off.

shit, I always lift heavy 4-8 reps and I dont ask for one cause I know what I can and can't lift and I will just cheat to get myself out of a bind (if need be).

But if someone offers a spot, I won't say no. I would love one all the time but can't find a reliable partner so I need to know how to get out of "trouble" by myself.

anythign over 315 i ask for a spot just so i can force out extra reps and not worrie to much about killing my self but i have to make sure its someone i know that knows what there doing

last tues i did 405 for the first time and when i max out i like to pause in the botom motion its habit from highschool strength tests i think lol...but either way i did it one time with a pause and i did it clean no problem and i goto do it a second time with a pause and this kid puts his hands on the bar i said get ur fuckin hands off the bar i dont know why he did this when both times i did it i did it with ease and with a pause either way it pissed me off

sorry just had to add that

i usually stay within my limits, but if i decide to go over I don't hesitate to ask for a spot

I rairly get a spot but I know what weight I can handle. I don't know why guys use collers especially when benching. I never use them or maybe just when I'm doing curls to keep the weight from creeping down the bar.