Kingdom of Knuffel

So far, until you reach level 20, every point of xp you give to your knuffel is still just trying to pay it off.

The second you reach level 20, you can give it up for adoption and readopt it, and it will have paid for itself with a very small profit.

So far, every point of xp you give it PAST level 20, is gaining profit for yourself (but of course only give it up for adoption and readopt it right after it reaches a new level).

That's up to level 25, so far.

My prediction is level 30 is going to be fantastic and with diminishing returns thereafter, but I might be wrong. Let's find out!

Recap:

Rate of return is in the negatives through level 19.
At level 20: 0.10081
At level 21: 0.13711
At level 22: 0.16646
At level 23: 0.19033
At level 24: 0.20964
At level 25: 0.22537

3361xp to level 26.
Gain is 2k + 2.6k = 4.6k
Cost is 3.8k
Profit is 800

800/3361 gives rate of return = 0.23802

Recap:

Rate of return is in the negatives through level 19.
At level 20: 0.10081
At level 21: 0.13711
At level 22: 0.16646
At level 23: 0.19033
At level 24: 0.20964
At level 25: 0.22537
At level 26: 0.23802

3625xp to level 27.

Gain is 2k + 2.7k
Cost is 3.8k
Profit is 900

900/3625 = rate of return of 0.24828

(I'm rounding all of these to the 5th decimal place.)

Recap:

Rate of return is in the negatives through level 19.
At level 20: 0.10081
At level 21: 0.13711
At level 22: 0.16646
At level 23: 0.19033
At level 24: 0.20964
At level 25: 0.22537
At level 26: 0.23802
At level 27: 0.24828

3900 xp to level 28.

Gain is 2k + 2.8k = 4.8k
Cost is 3.8k
Profit is 1k

1k/3900 gives rate of return of 0.25641

4184xp to level 29.
Gain is 2k + 2.9k = 4.9k
Cost is 3.8k
Profit is 1.1k

1.1k/4184 = rate of return of 0.26291

Recap:

Rate of return is in the negatives through level 19.
At level 20: 0.10081
At level 21: 0.13711
At level 22: 0.16646
At level 23: 0.19033
At level 24: 0.20964
At level 25: 0.22537
At level 26: 0.23802
At level 27: 0.24828
At level 28: 0.25641
At level 29: 0.26291

4479xp to level 30.
Gain is 3k (1k at lvl 10, + 1k at lvl 20, + 1k at lvl 30) + 3k = 6k
Cost is 3.8k
Profit is 2.2k

2.2k / 4479 = rate of return of 0.49118