The so-called sandcast models were the first 7414 produced for the 1969 model year, all later bikes would use die-cast engine molds. As a relatively rare "thing" for such a historically important motorcycle, these early bikes understandably have a higher collector value. That value has steadily increased over the years, now at about $40,000 for an original or well-done restoration. So, we again see the magic of the McQueen mystique. This particular example has ownership documentation but was subsequently purchased from McQueen's production company in 1971, so his was a short-term affair. Additionally, this bike has had a full restoration so any originality is gone beyond the engine and frame numbers.
Value is not real, it is a perceived reality. Value can't be touched or quantified, it can only be felt. Purchases like this are made from emotional or investment considerations and a McQueen vehicle combines the two. To the fortunate few, money is a secondary consideration, simply the price of acquisition. $155,000 to those folks is probably like $5000 to most of us — it's just not a big deal, and as long as Steve McQueen's name continues to add value, the "investment" dollars are safe. Well sold.