Recently, someone has been watching large on-chain transfers and hot/cold wallets on exchanges and immediately saying "Smart money is coming" whenever there's movement... I find it a bit exhausting.

Back to the cross-chain issue, especially IBC / message passing / bridges, to put it simply, it's not just about "moving tokens over," you're trusting a series of components: the source chain and target chain not having issues, the light client / validation rules not being broken, the relayer not messing up or stopping, and also the bridge contracts / multi-signatures / oracles and other intermediaries not getting hacked.
If any one link loosens, it's not just a slow burn that can be tolerated; it's a direct jump to failure.
I see complexity as an enemy: if you can avoid cross-chain, don't cross; if you must, try to choose chains with shorter trust chains and clear boundaries, avoid too many "re-staking and stacking buffs" tricks, and sleep more peacefully.