There are lots of benefits for space exploration. Yes it is really costly but we have to break down the benefits of space exploration so that we can justify the costs and the risks of it. Below are some of the benefits of space explorations.
1. advanced communication- space exploration are looking for the most efficient way on how to deal on wireless communication. If This would stop, our wireless communication features will stop growing as well.
2. protection from outer space attack- not the alien thing but the possibility of an asteroid to hit the earth. Yes it can be performed without sending people/machines outside the earth. Installing/sending unmanned robots to other parts of the space would be very helpful in detecting probable asteroid hit in the earth accurately.
3. Improvements on human living. Space explorations can aid in predicting natural calamities such as flood, storms, and wild fires. Forecasting of weather should be of high accuracy and space exploration can deal with that.
You can post this question in the discussion so that you would hear many ideas from the people in the site :)