The money arrives after you have already spent it.
You paid the band’s deposit in June. You pay the sound engineer and the bar staff on the night. The tickets sold in July. On most platforms that money is released three business days after the show ends and takes another three to five to reach your bank, which means the sale you made thirty days early lands thirty-three days late.
You financed somebody else’s float with your own box office. On Gatehouse there is no float, because the money was never pooled: it is in your Stripe balance when the card clears.