If I move to America, can I buy some land somewhere, put up a fence and signs that says "trespassers will be shot no warning" - lure people in with a display of money trees whatnot .. and then just *kill* everyone who jumps the fence - no repercussions? Texas?
Depends on the state.
Texas = yes, but
So Texas you are allowed to use force to terminate trespassing or theft.
However, if the trespasser flees before grabbing any of your items (aka money tree), the trespass is considered ended and you are not allowed to execute them at will.
You need to make sure they are not fleeing when you shoot them. There is no obligation to warn them, ambushing with a DMR is a sound
offensive move self defense tactic. This is best proved by recording the
merciless execution heroic self defense. It is also best to make sure the person you
viciously murder defend yourself from is not white.
That almost makes me wanna get the paperwork started.
However, the biggest and by far and away largest problem with your plan is you will need to live in Texas. Because of the exceptionally poor and unreliable services, you will need to prep yourself for:
freezing weather
unpassable roads
electrical grid failure
natural gas pipeline failure
gasoline station failure
grocery store failure
complete societal failure
Keep in mind that you are not a native Texan, so when things get tight it will be considered acceptable to murder you and take your stuff.