LRC is used to pay gas on the Loopring network, similar to how ETH is used to pay gas on the Ethereum network. Loopring is a Layer-2 solution, which basically means it's a chain built on top of Ethereum. Why use it? It has much cheaper fees while being able to do all of the same things and maintaining an acceptable amount of security. There are other L2s of course but LRC is partnered with GME so everyone here likes it more than the other L2s. You would want to buy it over Ethereum for investment purposes because the potential gains would be much higher, given the lesser current adoption and therefore a greater amount of future adoption, and the fact that it's much smaller cap so there's more potential in the market cap multiplying. That also does mean it carries more risk than Ethereum, which already carries quite a bit of risk in and of itself.