OK so I'm level 28. Town Hall 6 costs 750,000 gold. I can have 5 gold generators and currently they are upgraded to level 8 - producing 1900/hour.
That's 9,500 gold / hour. At a needed 750,000 gold we have 3.25 days I cannot spend gold *OR BE ATTACKED* to be able to upgrade. Perhaps this is what is intended - that you buy a shield for that time and then AFK (though I can't imagine that's a very fun game - a game I don't play for 3 days).
So let's say instead you try and make it from attacking.
Finding a new opponent (at my level) costs 170 gold. When I search for opponents almost 80% of them have less than 10k gold - I've found a very few rare "suckers" with a few tens of thousand gold. Remember, I said we need 750k to get to town hall 6.
I CAN make gold attacking people, but I have to spend it or else it's stolen from me. I've taken to only using archers since they are so cheap and I can win with them at this level.
So instead of producing this 750k let's say we attack for it. Assuming there's no cost to find a new opponent (there is, 170 at this level) and assuming we aren't attacked (we are, I usually get attacked within 30-60 minutes of my shield being down) and finally assuming we can net about 10k-20k / attack - that's 37-75 attacks before we can upgrade.
Given it takes rebuild time to rebuild your army between attacks (I said I'm using fast and cheap archers though, so build time is minimal) we can attack about once every 20 minutes. That works out to be about 12 hours required of finding 10-20k gold targets wherein I'm never attacked.
So what am I misunderstanding? Because I can't see any of these conditions as true - yet there are clearly people with TH >= level 6.
Please inform me.