If they are walking past I let it slide. If they stop I say "Yes, I like it. What do you use for photography?" Then I immediately think of a couple of good things to say about their chosen weapon, even if it's a phone.
If a chat gets going, I soon ask how important is a good photograph to them. If the answer is 'not really', there is no point in embarking on a tale of my equivalent of your Four Year Journey. If they are pretty keen, I give them a nutshell encapsulation of what my kind of kit gives me in exchange for so much bulk, weight, and cost, that I cannot get out of their camera, nice as it may be.