All combat positions involve a high amount of stress. Tank Commanders are no exception. In addition to the stress of constantly being a major target for enemy troops, Tank Commanders also have to consistently perform well, making split-second decisions that can (and will) affect the outcome of battle. In addition, Tank Commanders are responsible for the lives and well being of their crews. One miscalculation and your friends and co-workers can end up buried in tons of mangled steel.
There's also the impact that a Tank Commander’s actions has on the rest of their platoon or on other soldiers in battle. Hundreds or thousands of lives might depend on the decisions made inside of a single tank and any misstep will have to be answered for with a Commander’s superiors. There are more stressful jobs, but they usually involve juggling chainsaws.