The big one I do is medical tourism, though I have family in Taiwan. I've done a bit of dental works where the cost in the US is $3k-$5k after insurance, and at Taiwan is maybe $300-$500 (10x diff) cash pay. I've also done scan-all-the-things health spas in a Taiwan hospital for $300-$500, where American equivalents are again 10x.
So he bought me (19) and little brother (16) tickets to fly from Amsterdam to New York (2x350) and get a cheap hotel for 2 nights (2x100). All to get a Thinkpad W500(?).
We had a great time. Got chased by a wild homeless person on Staten Island who followed us onto the ferry and we were scared stiff. Also walked all over Manhattan. Went to the Bronx but got stared at a lot so quickly went back to the subway. I can still hear the iconic "Stand clear of the Closing Doors" in my head.
Too bad the America from those days is gone.
So there are individuals who do that and it makes sense (if you enjoy the flying / traveling) and it's not considered "time is money"
There are also common parallel importing in many countries who find a dealer at some country that has the same product in lower local currency, buy bulk and get some discount, then resell it in the country where the official distribution is expensive.
That's why it is possible to find no eSIM/NFC iPhones in some stores (imported from China) or eSIM only ones in regions where you'd expect them to have also physical sim tray.
The poster says that the 28 TB Seagate HDDs have been bought from Best Buy and B&H for around USD 330.
If I look right now at Amazon USA and Newegg, I see much higher prices, in the range of $600 to $700, so buying from there would be a mistake.
However, the reported price seems too good to be true, because looking now at both the B&H & Best Buy online shops I see prices double in comparison with the claimed $330, and which are in line with Newegg and Amazon USA.
So perhaps the poster was extremely lucky and has succeeded to take advantage of some price that was so low only for a short time.
For comparison, last week I have also bought a 28 TB Seagate Expansion HDD, but in the European Union, for USD 550, which is much lower in comparison with the UK price of almost $770 quoted by the Reddit poster, and also much lower than the prices that are listed today on Amazon USA, Newegg, B&H and Best Buy, which are higher by about 10% than what I paid.
On the other hand the Reddit poster has succeeded to buy 10 such HDDs for a price of only 60% of mine, raised after that to about 74% by the import VAT.
Good for him, but taking into account the prices that I see today at 4 US online shops and the continuous price increases in HDDs, it seems that not many, if anyone, will repeat soon such an achievement.