Yeah Thanos got into a tussle with the Champion, I freely admit I forgot that particular fight happened there, however the entire point was to get Champion to destroy the planet, stranding himself in the middle of space. He didn't intend to just beat the gem off of him(and indeed, Champion essentially no sold everything Thanos did to him)
Again this was Champion, he's cosmic Rhino, super strong, dumb as a box of hammers, didn't know how the Power Gem worked and didn't realize it did actually work. The reality gem is a great deal more dangerous if the user is remotely competent.
This is how that encounter ended:
And that's the only time Thanos went after an infinity gem via the direct route.