Beyond what you have done, I think 1) emergency wheel truing and spoke replacement, 2) chain repair, 3) shift cable adjustment/replacement, 4) brake adjustment (no particular order, though working brakes should be at the top).
But perhaps more important is an awareness of all parts of the bike. I get a few warmshowers guests whose bikes are near failure and they don't know it--very loose headsets, failing bottom brackets, loose wheel bearings, end-of-life chains and cassettes. I often convince them to spend an extra day and use my tools and stand.
Look for a non-profit bike shop or coop in your area to volunteer at, if at all possible.
Of course, your friend's method is certainly valid. Mechanical failures can be just part of the adventure. You may make a new friend.