Because there have been tons of new advancements in medicine....
And advancements in agriculture...
More people can live on the earth now because there's more food and vaccines for diseases!
Nowadays, technology like smartphones and computers are available to many people across the world
however, all of these electronics use electricity. With so many people in the world using this much electricity, the world energy consumption has gone up drastically.
These new technologies are even available to people in third world countries
The USA only has about 5% of the Earth's population, yet has almost 20% of the global energy consumption. This is because the lifestyle we are accustomed to living requires a very large amound of energy to sustain.
Sooner or later, the fossil fuels we burn to make electricity will run out. That is why we either need to change our lifestyle or create sustainable alternatives for energy.