My motivation? Simply showing my positions after being accused of being short when I had no TSLA position or people accusing me of "being short since $20-30". I can't add a disclosure line to every comment I make on SA, it's simpler to add it here.
As for luck vs skill: I have been in the stock market since 1988 (although I could only buy a few stocks back then as a teenager), so I have some experience. However, I think many people retro-actively attribute their winning trades to skill and forget about luck. A good book has been written on the topic recently (no relation to the author):
Luck and Skill Untangled: The Science of Success - Wired Science
I do look at valuation numbers (PEG, EV/EBITDA...), running DCF on a few future scenarios, company news and management, trading volumes, analyst estimates, institutional holdings and short positions, general stock market sentiment and outlook for regions the company generates future revenue and finally
simple technical analysis (I do not believe in hundreds of studies from Ichimoku clouds to Elliott waves) to create entry and exit points.
After all that, I still think luck plays a role.