You asked a direct question and I was rude enough to ramble on self-indulgently and vicariously; failing to respond.
The answer is very simple: the poor example of priests.
Ask anyone you know and they will give dozens of examples of hair-pulling exasperation at the attitudes, opinions,demeanours and actions of our beloved clergy.
But this leads to further necessary elucidation - and it's one fundamentally based upon the abandonment and abject neglect of our priests - the loneliness, despondency, the apparent futility of it all, the lack of support, their impotency and feelings of being virtually castrated or cuckolded in the modern world.
Their isolation from parishioners and a secular lifestyle - the reprehensible behaviour of associates who escape with a slapped hand or even promotion from the authorities.
The feelings of no sense of worth , the middle-age crises which seem to have no end , the disillusionment with their faith...
Everywhere one looks this is being demonstrably relayed from the pulpit - you don't know if you want to hug the priest or throw a bucket of ice-water over them.
All too often they appear to believe that they have no position of validity or worth - this is expressed through two ways - becoming dictatorial and tyrannical over minor procedural exigences, or just giving everything up into the hands of the laity...
Some barely survive through a 'happy medium' of these two expressions - others are jt disconsolate and seek succour elsewhere...Drink, food, isolation, tv, travel,unhealthily consorting too much with like-minded others, wasting money on inane aspirational projects, shopping, the internet, pornograpy or sexual liaisons where available, gambling...the list is endless.
But young men SEE these things ; parishioners witness all this and are highly antagonistic towards this outlook of the clergy and the contemporary church which is basically a milieu of neglect and abandonment
...and then there are the priests who ARE involved - the inner ring of reprobates who gave up thinking of God and the Church decades ago; caring more for liturgies and administration and educational/RCIA policies and all the committees,conferences and meetings involved.
...the young catholic man would rather choke on his own vomit than become one of these terrible speech makers or paper shufflers
...but what if he's lucky enough to encounter a good orthodox highly-motivated priest ? one who cares for and visits his parishioners, one who actually teaches and reveals his love of God and neighbour from the pulpit ?
All too often this accentuates the faults and failings of the majority of clerics around him - experiencing a good priest can concentrate all the crises in the church and make the young man more frustrated ; especially when he sees tht the priest is like an oasis, a voice crying in the wilderness; ridiculed and dismissed by associate priests, patronised by the authorities who are antagonistic to his anachronistic running of a parish; occasionally remonstrating with the priest for his failure to promote lay ministries and participation... the liberalising modernists have many ways of criticising/destroying anyone who is more capable or more loved than they are.
The young man confronts great risks and deeply questions his abilities - could he really endure a life like this ; with neither support nor comfort in any way - and what's more , all the things he truly believes a priest should be doing in the world seem to be thwarted or prevented even amongst the best of priests by the powers from above...young men are out there who are willing to become priests [irrespective of wanting to become them] but their wisdom perceives that they would hardly be given any opportunity to be the priest they truly thought they should be - idealistic, aspirational and devoted to God and the church - they see on the ground that everything that a priest should be is being proverbially urinated on, by the bishops, the laity and even the priests themselves...