There were at least two books for sure. I don't remember the author or the publishing year, but they were from the 20th century. The setting was in the somewhat distant future and the story followed two timelines:
The first one was when the main character, who was wildly rich, was in the office of a robot psychiatric counselor that was named after Sigmund Freud. They were trying to find out where the main character's depression came from. I remember the lots of complaining about how annoying the robot was and mildly rude remarks from time to time.
The second timeline was when the main character was young (~25 years old, I think). He had worked most of his life in oil mines (they made butter or something out of it). After winning the lottery he bought a couple of rounds at the pub and took the first shuttle to an alien space station that orbited Earth. There all major nations had sent all kinds of scientists and military forces under one global corporation.
The station had something like 1% Earth's gravity and was filled with 1, 3 and 5 seat alien ships, that people couldn't control a lot. Every ship had a predetermined destination that was locked in the nav computer, which people didn't understand. Everyone had a chance to go to the station and become an explorer (provided they could afford the shuttle ticket).
The point to it all was to see where the ships went, land with a lander module that was attached to the ships, scavenge for any remains of the alien civilization and bring them back to the station, where it was sold to labs on Earth to be studied. The corporation took a huge cut of every artifact sold, and it was illegal to sell it yourself.
After he finished the 1-2 week training program, the main character fell in love (kind of) with a girl on the station, that had experience (bracelets on the hand for every flight). He got a job as a grounds keeper, because he was scared of his first flight being a fatal failure. She was also scared to fail and had a job as a babysitter.
After some time and arguing with the girl, they decided to board a 5 seat ship, which they had to share with 2 or 3 gays. They took turns using the lander module to have some privacy during the flight (the ships didn't have a lot of room).