Peter McAllister Is a Mob Boss
Ultimately, this may make the most sense, and there is textual evidence to support it. The opening scene of Home Alone takes place in the family stronghold, with various mysteriously aligned brothers, sisters, cousins, aunts, and uncles moving at a breakneck pace, giving us, the viewer, very little time to acclimate ourselves to this large family unit. Bedlam is the name of the game. This is of course the “large gathering of a mob family” method utilized by Francis Ford Coppola in the opening scenes of all three of his Godfather films, and also used to great effect in episodes of the Sopranos.
Even more telling is the indifference each of the children feels when interacting with Harry, someone they assume is a policeman. These children have obviously been raised to think of the law as a joke, and lawmen as something to gawk at, fools with badges you should pester, ignore, or stonewall. You can almost imagine Fuller, the bedwetting cousin, informing Pesci that he intends to take the fifth.
And when his son is left behind, Peter’s not exactly happy, but he’s more or less calm throughout the entire affair. You get the feeling this isn’t his first rodeo in things going remarkably bad, and the experience of bouncing back before has instilled in him a certain confidence that everything is going to be alright. He’s right. No one would dare harm his son, or the full weight of the McCallister Crime Family would fall upon them.
When Peter finally notices the (fake) cop standing in his doorway, he saunters over to him without a care in the world, squints, and in a cocksure monotone asks, “Am I under arrest or something?” Of course he knows he’s not, because no lone city cop is taking Peter McCallister down. The contempt he has in his eyes for Pesci is clear. A couple of FBI Agents? That might have rattled Peter McCallister, but not some dope with a golden tooth. The Wet Bandits are such idiots they didn’t bother to do their research. It’s only their good luck that an eight-year old boy repelled them instead of Peter, who may have sent his goons after them. (In their first appearance in Home Alone 2: Lost In New York, the former Wet Bandits, Marv and Harry, are seen shivering and emerging from a truck full of frozen fish, surely an allusion to Luca Brasi sleeping with the fishes.)
Finally, when Peter returns to Chicago and finds that Kevin went shopping, he smiles briefly and says, “What a funny guy!” which brings to mind Joe Pesci’s epic rant in Goodfellas, the other important mobster film released in 1990.
So yes, when you examine the evidence, there’s really not much ambiguity. Peter McCallister is a gangster. That’s what he does. That’s why he is the way he is. That’s why he has that nice house. And that’s why dropping a hundred grand on two vacations is really no big deal to him. His anger that Kevin spent $900 on room service is thus, less about the price, and more about the terrible junk that Kevin wasted his blood money on.