When I see individuals not paying attention to proper form, there are usually a few things that run through my mind. For the sake of time, I will only discuss the thought that doesn't involve a boot up someone’s ass. Certain individuals refuse to accept the fact that their technique sucks and is only holding back their progress while putting them at greater risk for injury.
I feel that this is a self-esteem/ confidence issue. If the beginning of your weightlifting career was anything like mine, you probably started on your own, with no professional coaching your or correcting your technique. Did you honestly feel confident while performing the lifts? Did you really feel like a badass when squatting above parallel with knees caving in? Or did you feel somewhat ashamed, hoping that no one with real talent was watching you.
Andrew B. from Foundation Crossfit taught me how to squat correctly. After learning correct form, confidence was no longer something that was lacking in my lifts.
After a set of squats, if you aren't leaving the rack feeling like a beast, or at least confident that your form looked spectacular, then something needs to change immediately.
Athletes who use proper form tend to have high levels of confidence. What they believe about form is revealed through their technique.
These athletes lift for themselves, not to impress others. If they know that doing front squats with 200lbs pounds will do more for muscular development than slapping 8 plates on the leg press machine, then they will do the 200lb front squats.
They are interested in linear progression, not flexing their nuts at the gym. They don't care how they look when practicing jerks with 135lbs when their max is 345. They know that it will help with form and injury prevention, as well as improving overall technique.
This is one of the reasons why I hate coaching in a room with mirrors. Humans are biological creatures that are naturally attracted to moving objects and have a subconscious desire to look at what is moving. The thing that is moving is usually their reflection in the mirror. There is nothing uglier than a deadlift or squat performed while looking sideways at the mirror. Much better to be outside or in a room without mirrors, so all of your attention can be focused on feel/ technique. If you have a coach, then you absolutely don't need to be looking in a mirror while lifting.
Finally, these amazing athletes understand that lifting a big load with bad form will not help you lift big loads with proper form nearly as fast as always lifting with proper form. Obviously squatting above parallel will allow you to load more weight on the bar, but the difficulties and benefits are much greater when the exercise is done correctly. Like I have said before, big numbers are meaningless if you are sloppy Joe. The proper form has to be there before the big numbers can be.
Never sacrifice proper form for increased poundage. If you want to be an amazing athlete, then always look for ways to make an exercise harder, not easier. If you want an easy exercise that won't give you great results, you don't deserve to be under the first place. For example, bouncing the plates off the floor during multiple deadlifts will allow you to use more weight, but pausing on the floor will create more overload on the neuromuscular system.
If you want to be an amazing athlete, then your confidence needs to be shown through your lifts. No matter what weight is on the bar, if you aren't CONFIDENT in the form, then you need to change