The holodomor was started by the kulak class hoarding grain from the rest of the ukraine in a response to the soviets wanting to collectivise the farms in order to help feed the areas of the soviet union that were starving due to the autocratic rule of the tsars. In response to this completely avoidable hoarding of grain, stalin found an opportunity to wipe out the kulaks, a wealthy class of farmer.
Regardless of the disturbing outcome of the Holodomor famine, the ultimate causes of the crisis were created by man, particularly at the administartion level of the USSR. The policies implemented were unpopular, inefficient, and poorly managed. The deaths of the millions due to wide-spread starvation were the direct result of a program that was poorly designed, and horribly implemented. This was not a crisis caused as a result of a natural disaster or environmental crisis, Holodomor was a crisis created through bureaucracy.
Stalin caused the mass starvation of millions of Ukrainians in the early 30s that resulted in the Holodomor. While the newly created Soviet Union faced many challenges after WWI and revolution, rather than share resources among the people who needed them, Stalin insituted a reign of terror by attempting to wipe out entire groups of people, or to kill enough of them to keep people submissive to him. The Soviet authorities deliberately kept food from starving Ukrainians, which resulted in a famine on a massive scale.
Yes, the causes of the Holodomor was ultimately avoidable, because the food could have been distributed better. Other nations should have stepped in to solve the humanitarian crisis. Forced starvation is a massive humanitarian issue, and stronger nations should have declared war on the Ukraine in order to step in and solve the crisis.
The Holodomor was a completely man-made catastrophe imposed by Stalin and the Soviet system. The Soviet collectivist mentality viewed individuals as expendable, especially ones that Stalin did not completely trust, such as Ukrainians. The mass deaths were easily preventable had Stalin or the Soviet bureaucracy had any sympathy for the Ukrainian people.
Yes, I think that this extermination attempt was not avoidable. No one knew this was coming, but these to sides had been in conflict for a long time, so something was bound to happen. This was a horrible event, where people were killed by starvation, a horrible way to go.