What difference does the author point out between the youngsters of his generation and those of the new generation?

From the text:

When I was a young man, I used to listen to these tales from my elders, and take them in, and swallow them, and digest every word of them, and then come up for more; but the new generation do not seem to have the simple faith of the old times. We—George, Harris, and myself—took a “raw ’un” up with us once last season, and we plied him with the customary stretchers about the wonderful things we had done all the way up.

We gave him all the regular ones—the time-honoured lies that have done duty up the river with every boating-man for years past—and added seven entirely original ones that we had invented for ourselves, including a really quite likely story, founded, to a certain extent, on an all but true episode, which had actually happened in a modified degree some years ago to friends of ours—a story that a mere child could have believed without injuring itself, much.

And that young man mocked at them all, and wanted us to repeat the feats then and there, and to bet us ten to one that we didn’t.