For those of you that don't ride a motorcycle: when you're out on your bike you'll see other people on motorcycles wave to you. Doesn't much matter if you've got an excellent bike or a lousy one, a cruiser or a sport. They're just that friendly. Bear in mind that they're removing the hand that covers their clutch briefly to wave to you -- that's definitely a show of goodwill.
You can get a vague idea of what people like and value by what they talk about. You can get a more specific idea by watching what they do. You can get a really specific idea by seeing what they risk things of value for. You can be sure what they believe deep down by seeing what they're willing to risk life and limb for.
If you see another motorcyclist then you know that they've decided, "I'm willing to risk life and limb because it's fun and because the alternative is boring." Which is why you can look at them, knowing nothing else about them, and think to yourself, "that's my kind of person." And you wave.