Is the act of unaliving oneself easier than continuing to live?

killing oneself is often easier than continuing to live and endure life's hardships, because life contains so much suffering and each one of us has to strive to keep on living. I've read this claim in a psychology textbook, and it made me wonder if it's true or not, because for one, if it was true that it is in fact easier, then people would simply unalive themselves en masse, and yet we don't see that, albeit the increasing numbers of suicides annually. 

This appears to me to be a value judgment, not a logical inquiry. To make this a logical question, all the loosey-goosey underlying premises must be explicitly stated and evaluated. 

"Easy" is not the only measurement for a life valued. I go to the gym 6 days a week. This is not "easy" by any stretch, but I love it. I study spanish as an adult. This is not "easy", but I do it because, like exercise, the effort is well-worth the reward. Given this, killing one self does seem "easier" than living, but who cares?

"Suffering" is a certainly a better indicator of quality of life - perhaps the antithesis of well-being. When considering the overall quality and value of a life, one must consider both ends of the spectrum. We suffer in illness and when we lose those we love. We thrive in health and happiness, and when we welcome new life to our family. Then we also must consider many other factors such as one's resilience, attitude, level of hope or optimism, etc. Add in the moral elements, cultural and religious beliefs, and we have a very complex issue.

"Killing oneself is often easier than continuing to live and endure life's hardships, because life contains so much suffering and each one of us has to strive to keep on living" is sloppy communication that makes an implication but does not come close to accurately addressing the issue of suicide.

Is it easier? Depends on how you define easier. In terms of total effort you're expending, yes. Finding a bridge to throw yourself off of certainly is less effort than decades of working, self care, and maintaining relationships. However, evolution has granted humans a strong instinct to survive and to provide for future generations. The psychological hurdle someone would face in order to commit suicide would be insurmountable by many people. Particularly considering that humans also tend to be fearful of large changes, and will often gravitate towards a situation that is worse on balance because it's familiar.

I will partially agree with Bo's answer, and piggyback off of it. Humans don't just seek a life that's easy, or even free of suffering, but also one that is fulfilling. Relationships, helping others, accomplishment, material pleasures, they're all things that drive people to continue living, and in some cases, even suffering. Case in point, I spent a couple months caring for a terminally ill family member, and it took a tremendous toll on me physically and mentally. I could have chosen not to, but instead I chose to embrace the suck because I knew I was making a positive contribution to everyone in our orbit, and came out of it a stronger and more self-aware person without any regrets about what I did.

So, I think the fallacy here is primarily reducing desire to live to ease or comfort when the human experience is much more complex.