>"Lesson: Let people come to you. Let them have the need first."
That is not the lesson your experience. The lesson is the make sure there is demand before putting in a ton of time, especially when you're going to be bitter about it later.
Your project was doomed from the start.
You committed the time to build 5 websites and SEO them to the top spot before you had any demand.
If you had waited until a restuarant actually wanted a website, and then realized that even a small application can be made in a few hours for a few $hundred, then you may have had better results. Pre-emptively making websites or scripts is the opposite of what I've suggested.
So the next lesson is to not do work before getting paid (unless it is also a hobby - like building a database class that you will use in freelance projects).
I would have also approached selling the websites differently. Showing someone a website you're trying to sell them and then finishing with "I just need to change some pictures and stuff" isn't that compelling. You have 5 websites. Customize one for each restuarant you're talking to. They pass? Change it up with different pictures and titles. Let the customer see what they're buying, not some representation. This is more time consuming, but it will help sales. You already sunk time to designing, building, and SEOing the sites, so an additional unpaid 20 minutes probably won't hurt you too much.
Also you can't just assume why people didn't buy the websites. You should have done some random calling after the fact to determine why people weren't buying. But I will throw out a few ideas on that too.
You approached restaurants trying to sell them a commodity without knowing what they want. They could have not bought because of the price, because they didn't like the colors, they were intimidated by it's complexity, underwhelmed by its simplicity, or because they didn't think they needed a website (you really need to be making calls).
When someone comes to you with a budget and a need for a website, you are in a position of power. You can dictate more terms. Building a random websie without requirements or a scope and then approaching people takes the power out of your hands.
Finally, there are thousands of companies that don't have a website because they don't know how to make one or think they cost tens of thousands of dollars. These are the types of companies you can be trying to advertise to (but not cold call/approach).