This is done to ensure players aren't spending too much real money on the virtual gambling activities – even using the worst value GTA Online Shark Card available, exchanging the maximum GTA$50,000 for chips is only a rough equivalent of $1.50 / £1.00 so won't break the bank. When we purchased a GTA Online casino Penthouse and became a VIP, the maximum number of chips we could exchange became 50,000 but once again this cap is enforced every in-game day to stop any more chips from being purchased.
GTA Online casino chips are acquired by exchanging GTA$ with the cashier at a rate of 1 chip = GTA$1, and this was initially capped at a maximum of 20,000 chips in total per in-game day, which is 48 minutes in real time. While this method is arguably the highest paying in the game, it's also the easiest way to lose money fast if you don't do it properly.
These missions have the highest starting cost, but also the highest potential payout. Additional chips can be obtained from the Cashier Services booth on the casino floor, where you can also collect a visitor bonus once per day which is currently set to 1000 free chips. Import/Export is a newer way for the rich to get richer. When you first arrive in the casino, you'll get the option to purchase a Standard Membership from the Guest Services desk near the entrance or by following the on-screen prompt, which costs GTA$500 but gives you 5000 GTA Online casino chips to get started.