The problem is when all contributions are lumped into a single account actively buying and selling assets, "keeping track" of which assets are contributions vs conversions becomes impossible and difficult to justify.
Here is a better example:
In 2018 you do regular contributions of $1000 to a Roth IRA and actively trade securities with this money.
In 2019 you add $1000 via a Roth Conversion and continue actively trading securities with this money.
In 2020, let's say the overall account has decreased to now $1500.
If I withdraw my $1000 of regular contributions now, do I have some way to prove (??) that the $500 losses all came from the roth conversion money?
