Obviously.
However you do have to keep in mind that there are other methods of making more money with what you have than investing in a partyhat. A partyhat's value won't ever reach, say, $1,000 for a Purple. At least not for a really long time. However if you manage your money properly, you can turn your purple, let's say its 900M, into 1.5B in a matter of 3 months. Gaining an average of less than 1% daily which isn't hard, considering people's profits margin is higher than 1% daily. Purple has hit close to $1,000 when FT was released, but that was because of what no one saw what was coming. A massive stock of RSGP was in game, and people were overpaying per M ($1), and people with botted accounts used their GP to buy phats. Soon it settled down to where it should be, around $600 (Less right now).
But your Purple partyhat won't rise to 1.5B in 3 months.
Don't forget to take in account how much a partyhat's value was before Free Trade. All in all partyhats are pretty much the same value when RSGP was valued at $1/M before FT. A purple right now is around $450-500. It was about that much, I think it even was more, before FT. If you knew a method to transfer GP anyway.
The thing is Phats may rise in GP, but it would only keep up with either inflation or deflation. Deflation is happening because of the previous, and soon-to-come bot nuke. If you were to invest it elsewhere, the value of your GP would actually go up than stay at the same amount.