I think the worst case can result in a loss of braking on one axle due to fluid loss, but the sudden pedal drop leaves the driver believing he has no brakes. Catastrophic accidents can result.

More often, people assume that replacing pads equates to doing a brake job. It doesn't. You need to inspect all parts, look for problems, and identify things before they become bigger problems. If someone hasn't done a brake job before, it should really be done together with someone properly trained, who can help the first time. Brakes are a safety system.

Funniest rework I ever got was a vehicle with one of the front pads in backwards, ie friction material away from the rotor. It made a loud grinding noise. Rotor was trashed. Person had just done his own brake job, lol. You'd be amazed at what goes on out there.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue