Once again, they are the richest club in the world and can offer wages not many clubs can. It's just a matter of time before they will be back to challenging for the Top 4 in EPL.
Of all people Milan fan should know that spending a lot of money doesn't guarantee you anything. Right now they have a higher chance of relegating than staying in EPL, not to mention top 4.
It will take them yeas of spending before they can start thinking of top 4. Before that they need to establish a cash flow into club. I read that EPL will apply more restrictive rules not allowing owners to sponsor their own clubs even via third-parties. There is also FFP which will restrain them somewhat. If they spend too much in short period, they'll be out of EL/CL/ConL.
Then in EPL there is already huge competition. Liverpool, MC, Chelsea, MU, Arsenal, Tottenham also rich and won't give up top 4 easily.
Players also not stupid. They'll need guarantees at least of statying in EPL before going there. Most talented have interest from top clubs anyway, why would they risk playing in championship?