Couple of reasons
1. Unless you live in a big city with a thriving red light district, you have to actively hunt down hookers and that can be time consuming especially if you live in a small town where that shit doesn't exist or deep underground and tied to organized crime/the local drug trade (IE pill heads that suck dick for oxycotin and other drugs).
2. Hookers cost money and the better looking a hooker, the more she costs.
3. Hookers, especially those working solo and are willing to put their safety first before any offer of money, tend to screen clients and a freak like Chris Chan would never pass said screening unless a hooker was THAT fucking desperate for cash or felt sorry for him. There is a reason for the cliche that is "it's cheaper to marry a hooker who will divorce you and put you on the hook for alimony, than to stay single and pay big money for a weekly fuck session".
4. "Dating" a hooker can be super expensive. Even assuming Chris found one who would be desperate cash-wise to take him on as a regular client and Chris managing to avoid screwing up to cause he or her pimp to refuse to have anything to do with him no matter how much he offers to pay? That shit adds up fast and that's before situations where a hooker might try and extract money, gifts, expensive meals, vacations out of Chris.