NEW YORK, June 12 : In recent years, Elon Musk has been picky about whom he allowed to buy in to SpaceX, the rocket ship company making its highly anticipated stock market debut this week.One investor said that when SpaceX was privately held, he used a connection with a cousin of the billionaire entrepreneur to buy $10 million worth of stock in the satellite maker in 2018. A portfolio manager at a $500 billion U.S. fund said he had to use his relationship with a board member of the Musk-led Tesla for an allocation of SpaceX shares in 2023.Both pre-IPO investors said that even after getting their feet in the door, they had to visit SpaceX’s headquarters. There, in a reversal of roles, they were interviewed by Musk’s team, including CFO Bret Johnsen, before they were given the go-ahead to invest. Ultimately, they needed personal approval by the world’s richest person, and despite pouring in millions of dollars, they said they were given limited financial information about the company.Both of the investors — and at least 10 other pre-IPO investors interviewed by Reuters — are happy with the way things have turned out so far because the value of their investment has skyrocketed. Worth about $30 billion in 2018 when Lyndon Rive — Musk’s cousin and the former CEO of SolarCity, which is now part of Tesla Energy — sold his stake to the fund manager, SpaceX is expected to list at a market valuation of $1.75 trillion.