If not connected to the internet, no problems.
If connected to the internet, there will probably not be any problems for a little while. A couple months, maybe a year— but at some point, someone will inevitably find a security flaw that impacts the way you use the computer. Maybe a flaw that allows an advertisement you find on a website to infect you. But maybe a flaw that will enable anyone hunting for computers online to exploit, in which case just being connected to the net will be enough to get infected.
At this point, your computer will simultaneously be part of someone’s bot net, mining for cryptocurrency on someone else’s behalf, rented out for processing farms, and so on and so forth. You might also get hit with advertising Trojans and scriptkiddie shit, but it’s far more likely that the stuff they’ll infect you with will just syphon your processing power for their own purposes.