[DotDash]

For anyone actually interested in upgrading these cards, please be aware that the chance of success does not increase linearly from 0% to 100% based on how many points (cards) you invest.
It seems like (based on Iron cards only) for the first level of upgrade, there is a cutoff point at 45% success chance where each additional point invested in the upgrade attempt adds less to the upgrade chance.
Example:

I have an Iron Combinator card at upgrade level 0, which I want to get to level 1. The first 110 points give 10.26% chance of success (0.093% per invested point.) 468 points give a 43.63% chance, so still 0.093% per point.
More than doubling the card investment to 1034 points, only gives 66,83% chance of success, which means you are now getting 0.064% chance of success for each invested point. This keeps dropping until you eventually reach the 100% chance figure.

To complicate it further, when trying to upgrade a card to L2, there seems to be a bell curve, where the first points give the highest returns, then it dips, only to increase again somewhere between the 40% and 50% chance mark.

In both cases, it's more efficient (% for invested points) to take a number of lower level gambles, before the ROI starts dropping, than to invest the points for a 100% guaranteed upgrade.
I'm not a big fan of this layer of obfuscation (it doesn't state that the chance doesn't increase linearly) to what is basically another 'gatcha' element in the game.

Edit: it gets worse. I have a level 3 card. Investing more than half of the required points only gives 21% chance of success, so you're basically forced to invest the 100% chance amount. Why even still have a gambling element at this level, if four 20% gambles cost you more than twice the guaranteed upgrade? It's baffling.