Your kid will be grown up in less than 20 years, not 100. But even still, in 100 years, will there be 4x as many people? Will humanity be consuming 10x the energy that we do today? Will we have computers that are a million times faster?
The point is, exponential progress is incredible, but at some point it ceases to be exponential. And the progress of the last 100 years was fueled by a exponential population growth and exponential energy usage. We're already at +1.5C because of that; how hot will it be when your kid is grown up?