I understand how this system work but what you also need to understand is
1. Denjiro wasn't around 24/7
2. Some of the richest Wano citizens who visited Hoeyori probably came with their personal armies.
3. She wouldn't gather so much money just for talking to them and sipping them some tea.
Denjiro didnt need to be around all the time.
As shown in the manga, the men gave the money to her because they intended to 'buy' her freedom from the redlight district and make her their wife.
She received their money for 'safekeeping' until they have gathered the neccessary amount, which was a fortune.
She didnt store the money for them tho, but used it for the cause.
This way she was able to remain a virgin and gather tons of money from these horny old coots, who didnt shy away from even selling their own families! I doubt they had any personal armies left lol