If not for the January 6 investigation we would not know that Trump stole top secret documents and took them to Mar-a-Lago.
If not for the January 6 investigation we would not know of credible claims that Trump tore up, burned, or otherwise destroyed or attempted to destroy documents required to be retained by law.
If not for the January 6 investigation we would not know that the Trump Administration had a plan to use the military to seize every election machine in the country and conduct the Administration's own recount of votes.
If not for the January 6 investigation we would not know that Trump planned to appoint the now sanctioned (for fraudulent claims about the election), attorney Sidney Powell, as a special prosecutor into election fraud. Powell herself is now the subject of a criminal investigation.
If not for the January 6 investigation we would not know that the Trump Campaign orchestrated the forging of fraudulent electoral college certificates and submitted the counterfeits to the National Archivist and Congress as authentic.
If not for the January 6 investigation we would not know of the still hidden dealings at the Willard Hotel "war room" up to and through January 6th.
If not for the January 6 investigation we would not know that Jim Jordan lied when he said he did not talk to Trump the morning of January 6th. We would not know why Jim Jordan tried so hard to be on the Committee, to cover his own culpability.
If not for the January 6 investigation we would not know of Sean Hannity's involvement, working with the Trump Administration, in efforts to overthrow the election results, or his ignored efforts to convince Trump to stop the insurrection.
If not for the January 6 investigation we would not know of the Russia connected OAN's role in drafting documents planning a military coup to overturn the election results.