A good business owner knows that tips are not always part of offering a service. There are those who offer generous tips and there are those who never give tips. Just because your client appears to have money to spend doesn't mean you're going to receive a tip.
If you're going into a job expecting a tip, you're setting yourself up for potential disappointment. You're in the service industry and offering a service in exchange for money. You shared with the client already how much your service is going to cost, so if you feel you deserve more, you should charge more. Offering to do additional services during the event does not always mean the client translates that into offering a tip.
Meal Prep Services: I can share with you in the history of the thousands of meal prep sessions I've performed, there has been maybe two families ever that left a tip at the end of meal prep service. Even if the person I was cooking for was given a gift certificate, they did not even think to offer a tip.
Private Events: When you go out to dinner, you may leave the server a 15-25% tip, but in the world of private dinners, the tips are often lower. My experience is that my regular clients, meaning those that I do meal prep for weekly, pay exactly the cost of the private event quoted to them, never to tip. If someone who is not my regular client hires me for a private event, there is usually a tip, but more in the 10-15% range. Of course there is the occasional super tipper, but it's a rarity and often occurs around the December holiday.
In summary, you should be charging clients what you feel your services are worth and if a tip emerges, bonus. Acting otherwise could be setting yourself up for disappointment.
Approaching a job like you "deserve" a tip is a red flag that you're either undercharging or you're in the wrong business.
It's wonderful to see perspectives on how others run their personal chef business. If you'd like to share your personal chef journey, I'd be honored to have you as the next guest post.