One of the guys I worked with at Veritas built a 28 footer that three people could travel in. It was good for a depth of 80 feet. He was dot.com multi-millionaire and I have no idea why he kept working.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
"I would like to die on Mars, just not on impact." Elon Musk