Thanks for your explanations, it looks pretty clear to me now. It seems that I have also been a tiny part of the solution, as Ive been using a Segwit address already for 6 weeks.
I would like to ask one question more: why has the hashing power increased in the past weeks? Ive googled about it and it seems that the power can be increased by new miners starting to mine bitcoin or switching to bitcoin but that seems unlikely to me because the price is lower now, so its not that profitable, right? Also, because of better hardware (more efficient) but I dont think there has been a significant hardware upgrade recently.