Spending Money as Freedom of Speech

I’m not familiar with law but it came up in another post that since lobbying congress is considered freedom of speech does that set precedent that all financial transactions are free speech?

If so, how could that impact the drug war, particularly asset forfeiture, if at all?

Could it impact how law enforcement could obtain evidence or prosecute?

Could buying cannabis where it’s banned, for instance, be considered free speech? Could arresting the consumer be considered a violation of free speech?

Of course possession charges would still be applicable, but could a private “conversation” between consenting adults be a justifiable reason to initiate a search or obtain a warrant?

Edit to continue…
How does that affect basic taxation? Is speech free if it’s a taxable action?