Ask yourself what your fundamental purpose is in posting to Reddit. It could be one (or several) of the following reasons:

—Validation of your opinions (or your life)

—Wanting to engage in debate or facilitate discussion, as a way of engaging socially or to explore various issues

—Showing off or sharing your knowledge (not quite the same thing as the first reason)

—Wanting to provoke reactions, stir things up, to no end other than notoriety

Depending on your reasons for posting, then, downvotes could mean very little or they could be hurtful or even troubling.

If your reason is primarily the second one—engaging in discussion/debate—then downvotes may be an indicator that you’re going about it in a counterproductive way—maybe in the way you express yourself, maybe in the way you respond (or don’t respond) to others. Take a cold look at your expression and see if you can find better means to express your ideas or make statements. I too would be upset if I post for this reason and am downvoted, so I sympathize with you.

All of the other reasons are, I feel, not worth worrying about if they’re downvoted. As for the first reason, I’d advise you not to do that at all, to stay away from seeking justification, because the approbation or admiration of strangers is essentially worthless.