Any team at a distance will lose to a top club for only one reason - squad depth/reserves. In almost every season, you can see a couple of bright teams that overtake the leaders but by the end of the season experience big failures and give way to leadership (exceptions like Leicester happen but very rarely). And this is only a matter of resources and not mentality. The mentality decides in knockout games.
Let's take Milan as an example, I don't think there is a very big, high-quality squad depth (like Inter or Juventus), but they had Ibrahimovic, this is a real leader with a winning mentality. Although he spent a lot of time on the bench, he is part of the team and he set the team up to win. Of course, it can be said that Milan had been knocked out of the European cups early and could have fully focused on Serie A, but even so, winning the Scudetto was not so easy.
Napoli for me is also a very complete team, I think the goalkeeper is one of the players that makes the difference, however I have full hope that this team will become much stronger, in that case with Milan it is our team that always It will be at the top for me, it is one of the most popular, of course Inter and Juve, they are teams that for me have a much higher level, their players are more active in terms of the most famous, we cannot forget that CR7 was there and he brought many victories, now with respect to his best players it would be good if they stayed in the team.