I am not sure people really can get better at trading to be honest. You can always tweak strategies and learn more,,, but usually the emotional side and discipline is the most important thing to fix and people cannot really do much to change the way they act (risk attitudes for example).
That is usually what gets you in the end!
One of the most important factor that should really be focused one but to know that everything should be balanced, from analysis to good emotion handling.Trading do involve lots of trials and error
where you can really enhanced up your emotional control as you do get involved with trading as years or days passed by.This isnt something that can be attain on a short span of time.
On the question of Altcoin loss become bitcoins gain then its most of the time this had been the case where market do shifts out but doesnt mean that it do happen from time to time.
Dominance or market trend doesnt really correlate each time because there are times that only bitcoin is rising but altcoin didnt really have any significant movement or just moving
sideways.