As our world becomes more dependent on technology, we start to need more materials. Most of these resources are non-renewable, meaning that once they're gone, they're gone. The practices for obtaining these resources also tend to destroy the ecosystems all around our planet. These practices, in addition to the actual production and usage of products also contributes to pollution.
Being sustainable means using renewable sources and using practices that prevent the destruction of our planet or protect Earth entirely. Having a sustainable mindset early in life makes it easier to have one as an adult and encourages the next generation of researchers and engineers to pursue new sustainable materials and practices.
As a robotics team, we use a lot of metal and plastic, which are not sustainable. With the resources available to us, it is difficult to find sustainable building materials that are as effective, and that we can afford. We don't let this stop us from exploring other ways in which we can be sustainable though.