This is really not a very good way to make money

You don't get softbanned for playing while being a passenger. At high velocity you can get speed locked, but that goes away in pretty much 1 minute after you slow down. Bus/tram inside a city won't ever get you speed locked, they don't go fast enough.

>lack of lucky eggs
Lucky for you there's a box at the store with 25 lucky eggs and 20 premium passes on sale. It's a complete steal.

>who would need them after it
Many players do. Most level 40s that I know are using lucky eggs to get more exp. It's just another way to compete with your peers.

Selling items back for coins is never going to happen. Don't dream about it. Trading items is also not going to happen because multiaccounters would abuse it to no end.

I'm level 37, and I've given up worrying about experience. I'm still doing simple things to get it, like evolving my 12s (Pidgey, Caterpie, Weedle, Wurmple, Whismer), and taking advantage of double XP to do more of that, but I'm not going to make a strong effort to get more. My feeling is that XP will come, once I hit 38, I can power up pokemon to level 40, and there's nothing in the game that I can't do. Levels 39 and 40 are just 'vanity' levels - they show you've played more, but don't give you anything else (as of now, and AFAIK - that could change.)

So I'll just let the XP come to me, like tomorrow's dawn. As long as I don't quit the game, I'll get there. Also, I'm using lucky eggs now to use them up. Haven't bought one (for the egg, that is) since about level 25 - using free ones, and the ones that came with the raid pass boxes. Also note, I'm f2p, so saving coin for raid passes, bag expansions, and so forth.

Lucky Eggs? They are the most useless items in the game. When i get them from gift boxes i trash them because past level 30 they are basically pointless, especially when you are on a big stardust budget run.