I disagree it is easy to land gear up. It is the most preventable accident there is.
At last someone with the balls to say it!
I've always maintained that landing gear up is totally avoidable and then someone trots out the cliched aphorism that 'there are those that have and those that will', making anyone saying they won't ever land gear up look incredibly smug.
I have had it bashed into me (like someone else posting here) to check out loud at 500ft that the gear is down:
In my case 'red, blue, greens'.
It may raise eyebrows from pax (as does my out-loud mantra on final of "height's good, speed's good. runway's good"- bashed into me by my PPL instructor 20+ years ago) but it's worked so far.....