What was great here, and something that played perfectly into the Eobard Thawne/Harrison Wells character, was what caused Wells to lose it with Barry, and even look to kill him, was the realisation that the plan he is working on ultimately fails.
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This is a man who is a genius, who has travelled back in time from the far future purely to get Barry Allen faster before finally killing him and returning to his own timeline. Wells is someone who just doesnt fail. Ever.
But as we all know, he does, largely due to the intervention of Eddie Thawne. Upon realizing that his worst nightmare has come true that he fails in a quest that he has put so much time and effort into Wells goes off the deep end, and it perfectly showcased the ego of this no-good rogue.