Every trek is different depending upon the location, weather, difficulty level etc. So the gear you bought earlier for some trek may not be good enough for your next adventure. For example, if you bought a sleeping bag rated 10 degrees Celsius which was good enough for your previous trek but will not work in colder temperatures. Similarly, the gear required for winter treks is entirely different from what you use in your summer treks. Renting gives you the flexibility to choose your gear as per the specific trek requirements which means you are always ready for an impromptu adventure.