[54351623]

Not an expert but here is an article on turning lead into gold. Spoiler it's radioactive.

https://www.scientificamerican.com/article/fact-or-fiction-l...

[chii]

For the energy cost, you might as well mine bitcoin instead of trying to make gold via nuclear reactions.

[avian]

Cost is more of a spoiler than radioactivity. At "one quadrillion dollars per ounce" you might as well do isotope separation and only collect stable gold 197. The additional cost of the separation would probably be just a rounding error in the whole thing.