[amsat-bb] LEO to HEO

Morning folks, I'm a relatively new ham and started following amsat only a few months so forgive something of a novice question.

The biggest trouble I see the community hitching a ride to a high orbit although low orbits seem to be easy to get. So my question is this, who says we can't launch a sat in LEO and design it to move itself up to a higher orbit? I mean if NASA can build probes capable of reaching mars, it stands to reason we can build a bird to move only a few thousand miles.

Thanks, Joshua Abraham, KJ4VYR