In Iron Man 2, it is revealed that in addition to the other parallels and contrasts that have been drawn between Tony Stark and Thanos, the arc reactor technology puts them on opposite sides of yet another issue. Thanos posits that overpopulation and competition for resources will lead to massive wars, starvation, misery, and suffering throughout the universe. His proposed solution is to eliminate the number of beings competing for these resources by half, and thereby avoid the suffering and misery that he saw as inevitable based upon his predictions. To that end, he collects the Infinity Stones, with the goal of performing this destruction supposedly randomly and instantly.
Exploring the character of Howard Stark in Iron Man 2, the audience is shown that Howard came to the same realization - but with a different conclusion. Influential enough in the scientific community within the MCU that Wakanda investigated his mysterious death, Howard also realized that conflict over limited resources was bound to lead to further war on Earth, and planned to use arc reactor technology, combined with his studies of the tesseract carrying the Space Stone, to create limitless free energy. Since Howard lacked the resources to fabricate an element that could mimic the energy output of the Space Stone, it ended up being Tony Stark who solved that puzzle.
While energy isn't the only resource that people could end up competing over, this highlights a distinct difference between the two characters that sets them up in opposing roles. Thanos chooses to reduce demand, while Howard and Tony choose to increase supply. The Avengers, where he sets a miniaturized arc reactor to work underwater to provide clean and renewable energy to Stark Tower, with the implication that he is using his personal office building as a test case to showcase this as an energy solution for the entire world.
In addition to not requiring an unprecedented wave of death to sweep over the universe, the Stark strategy could likely have built outward with an increased understanding of the other Infinity Stones. The new-element arc reactor was built using an understanding of the Space Stone, but further study could have provided further powers, synthesized and democratized.
It's impossible to say for sure whether the Stark strategy would ultimately work, but the Avengers: Endgame.
This is just another point of contrast between Thanos and Iron Man, setting up a contrasting parallel between them, but it's interesting to see that the groundwork for this contrast in parallels is an inherent part of Tony Stark's backstory, and that the wheels were in motion for this contrast as early as Iron Man 2.
