Someone can create a bunch of them, using some evasive techniques to avoid Google identifying them as one person.

When people call asking for service, that's a potential lead. This info could be sold to a contractor.

The other piece is making the GBP compelling enough--through fake reviews, submitted by web browsers running on separate IPs--to have folks contact them.

More ambitiously, the person doing this creates their own business, hiring out service crews to do the work and capturing more of the profit.