@MataiceAlison If a person win 1000 levels per year (90 levels per month), of course it will take 4 years to get to level 4000... But I can win more than 90 levels per month!
This is a pretty impossible question to give a standard reply to, as people's experiences and gaming habits vary so wildly. So we can only really give our own individual take on this.
I started playing Candy Crush Saga on 21 September 2017, reached level 2000 on 10 February 2018, level 3000 on 7 March 2018, and level 4010 on 22 November 2018 (at that time 4010 was the highest level available on mobile). So for me it took a year and two months. I have a full-time job and also family obligations, so without those maybe could have done it faster. Although now that I see those dates, I realize I did 1000 levels in less than four weeks. Had forgotten about that. I think that in that month I probably did not read many books..