Whether or not you are worthless is something only you can decide.
Nevertheless, it's important that you pace yourself and refrain from placing all of your worth on contests alone. From what I've read, these contests seem to be eating you up - keep participating, but at the same time don't make webcomics just for these contests.
The majority of webcomic artists are working on their projects because they have a natural passion for it and view popularity as a second priority - the whole business is a slow burn, and it takes quite a while to establish yourself. Take a walking pace.
Additionally:
This is a given in pretty much everything - the more generic something is, the more people will relate to it. Pair this factor with good execution and you have a hit that will attract millions.
With this in mind, know that if you're going to do something unique, you have to ensure that it is executed with finesse and skill. This is harder than going down the generic route, but it's a road worth travelling - just be aware of its difficulty.
Do not blame your failures on the exploits of the winners - rather, focus on what you may improve on yourself, while drawing inspiration from various sources - even these supposed winners would be worth studying.
Back to the topic of webcomics being a slow burn thing though, I'll end this post with a brief blog section of mine:
What you see above you is the humble beginnings of my current webcomic, Project SHaDe. Started out of boredom during my first year in highschool (13 year old), this was my first shot at making comics, a passion that I had been meaning to pursue since a very young age.
However, I had many obstacles in my path at the time - most obviously, a complete lack of artistic refinement, an absence of a clear-cut vision for the comic (at most, it was a whacky comedic adventure), as well as numerous doubts as to whether I could make it.
Furthermore, I was furiously jealous of Japan - in that they have a large market for manga and a wide range of opportunities for people to become manga artists themselves. Compare that to a Kangaroo Island named 'Australia' and you'll find that in this large continent I am living in, the general populace gives no damns about comics - at most, old people laughed at the mini comics in their newspapers.
At the time I began releasing the comic, there was absolutely nothing in terms of attention - deviantArt was a generally unsuitable platform for comics, and my lack of clout meant that no one even read the comic in the first place.
In spite of this, I continued refining my skills and improving my story-telling abilities - I studied and observed acutely the media I consumed, and drew everyday with an almost obsessive force.
These improvements would be codified through the notion that I have overhauled and revamped this comic 4 times, including the current iteration that is Project SHaDe
Whilst I improved on this project, I managed to make a 'break' of sorts through the webcomic field in the form of a one-shot named Catma
Originally made for an international Shonen Jump contest last year (which I failed to submit on time), I continued to work on this comic a page at a time, posting it here on Tapas. It was only after it was briefly placed in the Trending page that readers began to pour in and enjoy themselves with the work. One lesson to learn from this is to make a few short experiments to garner the interest of potential readers - they may carry on to your main projects.
And thus, after these 5 years, as well as the aid of Catma, these are now the extent of my skills:
Notice that even then, after all these years, the artwork is not necessarily at a professional level - there are various areas of my work that I desperately need to improve, and there are still many ways in which I can refine the narrative flow of the work - however, I can say with certainty that the struggling with myself and the numerous pages of blank paper I had laid down before me were worth it - in fact, they were integral to bringing me to this point in the first place.
If there is one thing I would like you to learn from this shitty blogpost, it's that the only way to mentally survive creating webcomics is to consistently march forward, taking things one step at a time, while also taking said steps with great deliberation.
In spite of the 5 years I spent making comics and art, I am not some huge success in the broad scope of things - I am still a little fish with a long way to go. To be frank, I'm not sure whether I ever will become a big fish, but I know for sure that the right thing to do is to keep swimming.
So don't give up - this is not something that only applies to you - I believe this is something that applies to everyone that's reading this. Take one step at a time.