You still need rubber wheels when it's stopped and at low speed. They retract when it's fast enough for the maglev to take over.

The electrical conductors are expensive as shit. The ones in the train need to be super cooled or something. The track ones need to be built along the entire length. On three sides, one vertically and two horizontally. Along with massive power lines along the whole length. They don't need to move to be expensive.

The right of way needs to be very straight. So compared to normal high speed, you have to spend much more on buying land, earth moving, tunneling, etc.

All this needs to be maintained to an extremely high degree because you can't accept a failure. The engine on a high speed rail fails and you just slow down, no biggie. HSR track is fairly robust and can easily be inspected visually. Since it has the same base as normal passenger and freight you have an entire industry knowledge and inspection machines. Any part of maglev fails and you have a catastrophic failure.