Because not all blocks can be full, we are looking for 0.5 TB in next 6 years when users will probably have 10-100 TB HDDs in 6 years. If someone really think a bit technically about it and dont spread the FUD about decentralization and how Bitcoin cant scale anyway with onchain transanctions, he would come to conclusion let scale onchain transanctions as much as possible to still keep decentralization - 0.5 TB HDD storage in next 6 years will not break decentralization, even 1TB or 2 TB in next 6 years will not break decentralization either

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This is "FUD". You're working under the assumption that: 1. The block size will remain at 2 MB for 6 years (while saying that 1 MB hurts adoption). 2. The HDD capacity is going to increase tenfold in 6 years? 3. This doesn't hurt decentralization. You obviously are not thinking properly because there are a lot of factors to consider.
What about new nodes? Good luck catching up with a 0.63 TB network on a raspberry PI. This is something that can not be left out (among other things). In other words, this does hurt decentralization and that is a fact. The question is just how much and is it negligible?
1. It can safely be adjusted up to 8 MB when needed and still only
maximum 2TB of data every 6 years. The point was as long as user natural HDD capacity is increased over time, so can be blocksize limit to be increased to keep the same level of decentralization.
2. I have 2 TB storage but I guess average might be well above 1 TB today. At least 5x increase is reasonable in 6 years
3. Rasperi PIs are dead path for the most successfull crypto imo. You dont release best games with minimum system requirements so you can please everybody. You stick to something like top 75% of user PC market and only this way you can release top product played by most. Releasing India game with basically no minimum system requirements will not give you a better seller...