So not only did we beat them in a war, we paid them for the land in cash.
Case closed.
L
And part of the "deal" concluded with the treaty was that the victorious American forces would leave Mexico City and the rest of the territory we had taken during the war. That's a pretty good deal for them, we could have just kept it as a subjugated colony.
(Hisotrical fact: Mexico in 1846 had a much larger professional military than the USA. We whipped their a$$es back to their capital with hastily formed and trained volunteers and amateurs. Something they may wish to think about, should push come to shove again.)