The issue with spacetravel is that A: getting off planets is extremely difficult, and B: distances are extremely long.

All technology that exists right now forces us to burn a high multiple of fuel in your weight to get away from earth (if you weight 100lb then you need about 1500lb of fuel just to get you off the planet, and the same applies for everything you want to take with you, on smaller planets it's a little better though). Escaping gravity is a tough task.

The other issue is that space is huge. To get to Mars with the current in technology we take about 3 months. To get to the nearest other star at the maximum physically possible speed you take 4 years!