Yes, pride is a sin, and ALL sin is deadly.
The soul who sins shall die. ... (Ezekiel 18:20, ESV)
I'm a sinner. I deserve Hell. But no, you won't be seeing me there, agentCDE, because unlike you I am blood-bought and my sins are paid for. In any case, my 'treasures in Heaven' comment was not prideful whatsoever. It's based on an imperative from Christ Himself:
“Do not lay up for yourselves treasures on earth, where moth and rust destroy and where thieves break in and steal, but lay up for yourselves treasures in heaven, where neither moth nor rust destroys and where thieves do not break in and steal. (Matthew 6:19-20, ESV)
I'm saved by grace, and I serve by grace; in that, God is glorified and His people filled with joy. And in fact, it's you guys doing the work for me. I just have to sit back and take it in. But hey, as much as I appreciate all the benefits I get from your attacks, you're not helping yourselves out too much, because according to Jesus:
And the King will answer them, Truly, I say to you, as you did it to one of the least of these my brothers, you did it to me.’ (Matthew 25:40, ESV)