I built the circuit in LTSpice with a 4.7V Zener (1N750) - 3.75V output - and a 100 Ohm load. I am getting a peak power in that transistor of 1.8W, but if I ctrl-click the waveform expression, it shows an average power of 6.33mW. The peak collector current is -430mA at startup and -220mA once it has stabilized, which is well within the maximum for most higher-power TO-92 transistors. The maximum power is related to the maximum temperature, so it's the average that will damage the transistor, not the peak.