9th Jan to 18th Mar: I concur, that is the inherent BTC increase rate.

Your blue line is correct IMO.

If the USD doesn't crash one BTC will have a value of ca 1000 USD in a couple/few years. The blue line will even give the predicted month. Spike(s) could see an ATH over 1000 USD months in advance of the BTC value actually being so.

Fine graph.