Although that's certainly how some people will try to spin it. Venus' atmosphere is theorized to have begun much like Earth's
. The crucial difference was its proximity to the sun caused its water to mostly turn into vapor, instead of remain as a liquid. This (1) contributed to the greenhouse effect - water vapor is the biggest greenhouse gas contributor on Earth despite only a tiny fraction of our water being in vapor form, and (2) rose above heavier CO2 thus shielding it from being lost into space or being broken apart into its elements by solar radiation (Venus has almost no magnetosphere to protect it).
So Venus' CO2 was allowed to build up instead of being lost to space, eventually leading to the enormous pressures Venus has today. Mars's atmosphere has a similar composition (both are 96% CO2), but due to its weaker gravity and lack of water vapor, most of Mars' CO2 was lost into space giving Mars a surface atmospheric pressure only 0.6% that of Earth's.
Venus' surface pressure by contrast is 92 times Earth's atmospheric pressure at sea level. CO2's critical point
is at 73.9 bar (atmospheres) and 31 C, above which the difference between the gas and liquid phases disappears. So the CO2 "atmosphere" on Venus' surface is more like a sea of CO2 fluid (the Venera landers didn't even use parachutes for the final descent - they gently floated down using nothing but hull drag). You basically have the greenhouse effect of the CO2 gas, compressed into the higher density of liquid CO2. All made possible by excess water vapor early in Venus' early history.
Earth's early atmosphere was also nearly the same as on Mars and Venus
. But Earth retained liquid water, which was able to dissolve most of the CO2, creating the "habitable" conditions for life we have today. So it's actually liquid vs gaseous water which is the key difference, not CO2 levels. In fact Venus' present atmosphere is theorized to actually be much more hospitable. In the past when water vapor was still present, temperatures there were probably twice what they are today.