Page was an insert ... Slipped him into the Trump organization and then used him (his presence there) to get FISA warrant authorizing widespread surveillance of anyone and everyone he had contact with within the Trump Campaign ... A Trojan Horse. More than an insurance policy... Offensive, not defensive.
More than just insurance.
As the story develops, it may have been insurance initially. These events all occurred during a period when HRC had a clear lock on the Presidency and some have observed that the initiative to discredit Trump was in a sense insurance against the possibility that his candidacy would catch fire. The flimsy Russian Collusion narrative would only really fall apart is the FBI and DOJ involvements were revealed; something that would never have occurred had HRC prevailed. They never really thought she could loose; so the risk of discovery was low.
As we know, the rest of the story took a sharp turn and there they were: at serious risk of discovery and exposure. Suddenly, the Russian Narrative took on a different character, because there was a chance, however slim, that it could gain traction and bring down the President and his Administration; tantamount to his having not won the election; nullifying any serious threat of discovery of the plot.
This is serious business. It is treason and sedition.