I understand that. If losing a relegation series without demoting is equivalent to "demoting" and "bot promoting" then you'll have 2 effects conflicting: the demotion and the bot promotion (it's a fair assumption that if one is taken into account, also the other is). The end result is difficult to quantify, but I agree that you probably lose some revenues the following season. However since you can also build seats (if you're not capped) or generate profits with the extra revenues that should absorb some of the potential losses.
Both promoting league champions and teams that promoted from a bot cleanup will get the extra cash, though bot-promoted teams will not experience the same boost to their season ticket holders.
Long term beats short term strategies.
In Utopia there were a lot of top managers who chose not to promote and in order to boost their finance were focusing on road games. In a lower league, where you can win most of your road games because you can end 3rd but have no chance to beat the top 2 seeds, the best long term strategy might well be: win all the away games, focus on the cup and throw all the home games. Season after season. Until you see that you have a reasonable chance of going through the playoff first round.