A high roller is what every gambling venue owner either online or in a land based gaming environment is hoping to attract to their venue. This is a player who is prepared to play for very high stake limits. One of the benefits of being a high roller is that the gaming venues you choose to play at are going to bend over backwards to reward your custom.
You will often benefit from free hotel rooms at land based casinos when you are a high roller and all manner of additional extras which can also include free travel to and from the gaming venue. When playing casino games for very high stakes online you are likely to find you get increased comps and lower redemption rates for turning your comp points into bonus credits.