Let's calculate how long it would take on average from Novice without any investment if you rely solely on playing the game. To make it simpler I'm assuming one can achieve playing the league with the receive reward cards and buying cards with credits/dec at a 200 CP/$ ratio since I'm not calculating SPS airdrops into it. In addition, I pretend DEC stays at the current rate. Estimating Battle Rewards is tricky as well. My Assumption is 24 games a day with a 50% win rate. I'm fractionalizing the EOS chests.
League
Battle Reward/day
Chest Value
Daily chests
$ to advance
days to advance
Bronze 3
$0
$0.048
1.333
$5
79
Bronze 2
$0.0079
$0.059
1.466
$20
212
Bronze 1
$0.02
$0.07
1.6
$50
379
Silver 3
$0.0792
$0.100
2.8
$125
348
Silver 2
$0.1386
$0.110
4
$150
259
Silver 1
$0.2376
$0.120
5.2
$150
175
Gold 3
$0.396
$0.130
7.466
$250
182
Gold 2
$0.594
$0.140
8.733
$250
138
Gold 1
$0.792
$0.150
10
$250
110
Conclusion:
So in total, it takes 5 years and 56 days to advance from Spellbook to Diamond. That's quite a bit of time to get into Diamond. That's not including any non-game-related income opportunities. If you are serious about the game and use all the possibilities at hive and splinterlands offer us, 1-2 years should be achievable.