There is mention of a 48 VAC transformer above and the output, when rectified, is about 62V (plus or minus the filter capacitor and current draw/voltage drop. Nevertheless, a really big number.
When the PS is outputting, say, 1A at 1V, the pass transistor(s) drops 62V - 1V and dissipates 61 Watts (more or less). That's also a really big number.
That's why real power supplies use transformers with tapped secondaries and some number of relays that kick in at various voltage settings.
If you want to output 5V, there is no point in having more than 8v DC going into the pass transistor (more or less). Clearly, not 62V...