Is it worth doing a status run to make up those 150 ...
That 150 SC is going to cost you a around $1500, or a lot better if you can get some good routes.
Your Points earn on subsequent flights will be better. Also you get a few more free upgrades Flexi to J. You will also be Gold the year after next, even if you don't fly at all next year (soft landing), then softer landing to Silver. If you anticipate your flying will drop off, then Platinum could be justified to retain lounge membership, free bags etc for 2 more years.
As a Gold you already get free bags, so the only real benefits are J upgrades, and the extra points earn, which you could use to buy rewards flights, instead of using $A.
To achieve Platinum you need 1000 S/C, and flying 1 way SYD to MEL is $125. So 1000 SC costs at max (approx) $12500.00
You're $1500 away from Plat, from Gold. The Plat earn rate for points is 25% more of the base of Gold.
Spending $12500 as a gold** should get you approx 109,000 points. If you did the same thing next year you as a Plat you should get 125,000 points.
The value of 109,000 points is approx 10 SYD-MEL (10,400 points each) flights at cash $125 each = $1250.00
So the value of the extra points earned as a platinum on your spend is only $190.00 (So it's cost you $1500 for $190 of extra points)
BUT, If you like to fly J then platinum gives you 4 Flexi to J upgrades. If you MEL-PER or SYD-PER this is really good use of the upgrade from a $300 flexi to a $999 - $1300 J fare. (Value $1000), x 4 = $4000 value. (Current Special price of J MEL-Perth is $999, normally $1300.00)
These A330 J Upgrades would be costing you $657.00 ($1500 less $190 bonus points = $1310 / 4 = $327 plus Flexi $330 )
The upgrade path of SILVER to GOLD is much better value. You get lounge membership, extra bag kgs, extra points earn etc.
In this situation, the extra $1500 would be better spent on something else.
In this situation and many others, once you have reached GOLD or re-qualified as GOLD, your better to fly then on points and not worry about Platinum. To re-qual gold, you need to spend around $5000 on flights. That nets around 44,000 points. Which as above at $125 SYD-MEL (10,400) is worth $525 real A$.
At GOLD or PLAT level, points are essentially a 10% discount or bonus to what you've already spent.
Would I spend $1500 to get Platinum. No. Buy Virgin shares with the $1500.
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** We assume that you could spend $12500 as a Gold and still be Gold. This is not the case, as you would get enough SC to be plat. But for the simplicity of the equation we say you can.