If I score money as 0-1 and luck as 0-1000, then I have a possible overall score out of 1000.
If I score 0.3 on money and 600 on "luck" then I've scored 180 out of 1000, or 18%.
Or if both are 0-1 then I'd have scored 0.3 and 0.6, and overall scored 0.18 out of 1, which is still 18%, it's just the absolute number that has changed.
But the absolute number isn't important in a scale which doesn't have meaningful units.
Let's say you have 4 factors a, b, c, d.
If we are summing them then we can just sum them straight:
score = a + b + c + d
If we want to place more importance on some of them we weight them, with (constant) weights w, x, y, z by doing this:
score = w * a + x * b + y * c + z * d.
If it's a multiplicative relationship however then we multiply straight:
score = a * b * c * d
If we tried add weighting in the same way:
score = w * a * x * b * y * c * z * d
Then all we've done is scale the previous score by (w * x * y * z) which is constant, so hasn't actually affected any ranking.
To weight a multiplicative relationship requires the weights to be exponents:
score = a^w * b^x * c^y * d^z
The scores can be in [0..1] or [1..N], the increased weights still increase relative power of the input parameter.
If you take logs it's clear why.
log(score) = w * log(a) + ... + z * log(d) which is our weighting when summing again, and log is monotonic (proof of which is left to the reader), log(S1) < log(S2) implies S1 < S2.
Edit: Fixed formatting, it thinks * is italic.
a * (b * 1000) = (a * 1000) * b
Sorry, I hate bad maths, I realise it is just trying to imply that luck is more important, but in that case it should be * luck^n.