Spaceflight was solved decades before Elon was born. Reusable rockets weren't a hard problem--they were simply a problem the incumbents were unwilling to address because it would have massively cut into their revenues and profits.
Electric cars actually predated ICE cars. The issue with EVs was always the charging infrastructure, which Tesla solved...by simply throwing a lot of money at it. (Not hard, just resource intensive.) Their batteries are built by Panasonic.
Boring Co literally is just a used tunneling machine. They have literally not done anything with it except test it out below the SpaceX parking lot (and the innovation in boring would come not from the tunneling but with the post-tunneling construction of the tunnel walls, stations, dirt removal, and ultimate extraction of the boring machine).
Even at Paypal, their biggest innovation was developed by Musk's biggest pre-Paypal competitor (Thiel's company) before they merged to form PayPal.