The downside is money, Prebuilt systems are generally overpriced with low price-performance. If you link me the computer you’re looking at, I could tell you if it’s worth it.
Gaming computers generally have more powerful processors and better graphics. Is there a catch?
If you’re talking about a desktop system, then the main catch would be price. If you’re looking for a laptop, gaming laptops may have short battery life and get hot underneath during heavy usage, so check reviews carefully.
If you’re doing 3D or graphics work a Gaming Computer with its powerful 3D graphics might work out. You may also consider a Business Laptop, those have powerful processors and sometimes workstation 3D graphics. Business Laptops also have superior build quality, better construction, durability, and designs than normal or gaming laptops.
If you’re just doing office or internet work you don’t need powerful 3D graphics and the basic stuff will be fine.