I'd guess the Colecovion has a linear power supply which is known to be very large for the power delivered, and very inefficient. A quick search says the power supply was 28.5 watts. I'm typing this on a laptop with a 15 watt power supply (pinebook pro - about as low power as you can get in a laptop); connected to a USB hub with a 20 watt power supply!. My work laptop has a 240 watt power supply. I'm not sure what laptop you have, but I'd guess it can draw more power than a Colecovision if you worked it - but also that if all you were doing was running 10 Colecovion emulators it would draw less power.
We also should mention that our laptops have a screen built in and counted as part of the power consumption. The Colecovion expected to be connected to a power hungry CRT television.