I don't understand how lightspeed is maximum reachable velocity

No.13548932 ViewReplyOriginalReport
Okay something that's been on my mind since the first time I heard that nothing can move faster than light - 300000km/s
What's the point of reference supposed to be for that statement?
>pic related
If something can move at lightspeed there can exist other of that something moving at the same speed in the opposite direction, making both objects faster than light speed relative to eachother.
I know this is simple enough for someone to have thought about it before so it's just me being retarded and not a scientific breakthrough.
So to summarize my questions are:
>Where's the flaw in my logic
>What's the reference for that 300000km/s