So hopefully I can help you think about it. A couple thoughts. First, minting an iAsset (or any synthetic asset for example), really should not affect the price of the underlying asset (theoretically it could depending on how people choose to hedge positions, etc.). When you mint an iAsset, the price of that iAsset is coming from an Oracle, so I think you are all good there.
When that person mints the iCTB, they are actually borrowing the iCTB and are short iCTB versus their deposited collateral. If they wanted positive price exposure to iCTB, it would be easier to just go out and buy iCTB or CTB on the market. Minting massive amounts of iCTB may affect the supply/demand of the iCTB asset itself. This really matters less for price (because price is theoretically pegged, though it can deviate), but matters liquidity. It depends what they do with that minted iCTB. If they deposit into an LP, they are diluting any fee/emissions yield from that LP. If they instead went out and bought a bunch of iCTB on a DEX, they would see massive slippage and cause the price of iCTB to divert from the pegged price. This ideally would be fixed by arb’ers. Though i still need to wrap my head around it. I have a post out there about iAsset liquidity.
I put together a stylized example that really helped me understand the directional risks of minting an iAsset and liquidations of iAssets (when the CDP collateral ratio falls below the minimum). Hope this helps!
https://marco112358.medium.com/collateral-debt-position-cdp-and-liquidations-example-9c3585e3514e
here are my thoughts and questions around iAsset liquidity
https://forum.indigoprotocol.io/t/iasset-lp-liquidity-spiral/5465