You could argue that this is the age of social media, there are online shops, etc and promoting a brand shouldn't be an issue. But I think the actual problem remains the same, from the 90's till now : when a talented player thinks he's made it in football, that mentality impacts how much effort they think they should put to become a better player, because that shows that in that player's mind there's this attitude "Even as it is i am already good, people like me, i can be more expressive now" which often times cannot be further from the truth.
It used to be about drinking and becoming a model for a magazine. Now, showing off on social media and focusing on other things than football are the equivalent. Because it's not so much about what a player does but his point of view and how they see football. If you think you are a shit player, you are probably ashamed of being one of the 'jokers' on the pitch but if you think you are a special talent, 1% who's made it, etc, even if you're a shit player, you are probably already busy thinking about "how the big me can satisfy me better". This leads you to pursue other goals that often times are about glitters and fame. They're not even productive. In fact, they become a reason for abuse. Lingard didn't exactly build a successful clothing brand. They were offering sale up to 80% if I remember correctly, and the prices seemed to drop after streak of bad performances (surprise?)
Ultimately it's all about having the correct mentality. And believe it or not, mentality spreads so it's better to get rid of the negative influences. Professional sports aren't jokes. If you commit, you have a big set of rules and discipline to follow.