The downside is that presidential-level security for a public skyscraper in midtown Manhattan is far more difficult than more typical presidential residences. There are people who live in the building, and businesses that operate there, all of which mean there are visitors, members of the general public, deliveries and so on, who will come and go in that building and those adjoining it.
Those people are in for torment from the angry left and maybe worse whether the trumps are resident or not
That does seem problematic, although I have no problem with the Trump’s decision. There would be a cost associated with having the family in the WH, just as with Obama’s kids going to school there, so in that sense it’s a wash. Securing the building might become easier as those who live there who don’t wish to endure the added security measures might choose to relocate (I doubt there are rent controlled apts there ;-)) Trump Tower is certainly a target but on the other hand it is also “hidden in plain sight” so to speak, nothing is going to go in or out or over without being observed, recorded and hopefully dealt with.
i’m sure Trump has considered all of this.