are sins of impurity even the most severe of mortal sins?
is there even the ‘most severe mortal sin’?
Mortal sins are all severe, and all of them can be forgiven if you go for confession.
I’ve personally never heard of one mortal sin being worse than the other. I could be wrong.
But to answer your question in general
Some people fall into lust more easily than others. Some use porn as a coping mechanism. When they feel stressed, when they feel sad, bored, there are guys who turn to porn if they are angry at women etc. They turn to porn/lust. People who have more appropriate coping mechanisms won’t fall into it as easily as others.
And like most unhealthy coping mechanisms, it is difficult to stop.
My coping mechanism used to be cutting, it took me 3-4 years to stop. Even now I still get urges to do it. I believe it is the same thing for people who turn to porn or masturbation.
Some people simply have more will power than others, too.
Also, you can never be too sure that there are people who don’t commit mortal sins, especially lust. They choose to not tell people, and if they do it, they go to confession and try their hardest. Don’t compare yourself, we are all sinners lol. Focus on being as holy as possible. People do slip up. That’s why confession exist