The advantage of buying a GPU Rig instead of a Bitcoin Miner such as the Bitmain Antminer S9 is that the GPU Miner allows you to mine Altcoins, such as Ethereum, Monero, Expanse, and much more. These are considerably easier to mine with a GPU Rig compared to mining Bitcoin with a Bitcoin Rig. Altcoins can be 'traded' on exchanges for Bitcoin anyway if you desire.
Over the years your GPU Rig will allow you to mine the most valuable Altcoin at the time, by changing your pool settings in the config file, and even allows you a higher resale value because it consists of high-end graphics cards, motherboards, power supplies, frames and more that are easier to resell on the market than a Bitcoin Rig alone. Also, a Bitcoin Rig will have a certain power or hashrate to it, and over time this power will hash less and less as the difficulty factor of Bitcoin rises, the Bitcoin Rig will mine less and be less valuable for resale simultaneously.
With a GPU Rig, you can select coins that are meant for the small guys like us, giving us an advantage by trading Altcoins for Bitcoins in a tech-heavy market for years.”