Bro Napoli and inter Milan spending much in the transfer market means nothing, yes they have spent and sign good players but non of them are toping the league, so you never can tell, like you might be surprise that unexpected team from that league will win the trophy, and don't forget Juventus is out for business this time around so don't be so quick in conclusion as the league is still fresh.
Your explanation is actually wrong cause the money you see those teams spend is for a good reason and the players they have signed will help to strengthen their squad to fight for the league this season, they may not be on top of the league now of course you know that the league just started but you can't write off Napoli and Inter Milan in the league they are the favourite to win the league.
Exactly the money spent is an investment; as in any business, the investment can't be immediate.
It's right to spend on tactical acquisitions, renewing the team with fresh players or those who perform on the pitch.
However, many are convinced that one player makes the team, the worst thing you can think of in football.
I would also add that even by acquiring several players, the team doesn't necessarily function. It's not a video game; they're people, and it could be that they don't get along with the other players, the coach, or perhaps other members of the team. Obviously, we'll never know all of these things.