No it doesn't worth it for a solo player, as said Mandible it's almost impossible to build and equip an army for a solo player, how will i find those 10k? i need to trade before...
But if i buy 5 horses (about 2k) i can take 4 crates, that makes 24 goods that i can craft in a day, with 5 horses my speed is 44 and 99 with quickmarch, nobody can catch me, then i go to a really close fief where i can sold at 25 gold, it takes me less than 2 hours to make the round trip.
Even more, i don't have to worry about my path to avoid rivers, mountains, etc, one click to go, one click to come back (meaning i don't have to be on my computer all the time, only 5 mins then 2 hours later 5 min again).
2 x 5 mins for 500 gold a day with almost no risk.