People call bitcoin a store of value for a few reasons:
1. It's deflationary: there's a finite amount and as more coins are mined the cost of mining increases.
2. It's expensive and slow to trade: It's not viable for general purchases therefore it's main use is not in purchasing.
3. It's seen as a gateway cryptocurrency: Because it's the most abundant and accessible cryptocurrency, people often keep bitcoins in storage and then use them to buy other cryptocurrencies.
1. It's deflationary: there's a finite amount and as more coins are mined the cost of mining increases.
2. It's expensive and slow to trade: It's not viable for general purchases therefore it's main use is not in purchasing.
3. It's seen as a gateway cryptocurrency: Because it's the most abundant and accessible cryptocurrency, people often keep bitcoins in storage and then use them to buy other cryptocurrencies.
Only no.1 is correct here in my opinion.
Re: 2: Layer 2 solutions like the Lightning Network are the enabler for everyday purchasing, down to a micro level. The "crypto bros" will tell you that off-chain transactions are not the future but they are wrong. I have seen no solutions to this issue in other "cryptocurrencies" that do anything but centralise, and defeat the entire purpose.
Re: 3: That is how the "crypto" world sees Bitcoin, but I believe they are wrong. As layer 2 solutions proliferate, it will be far more useful to directly spend the best unit of account, rather than mess about with middle-man, centralised "cryptocurrencies". Your cold storage/node storage will be your savings account. Your Lightning wallet will be your cash in your pocket.
EDIT: Just realised 1 is not quite correct either. If the cost of mining increases it is likely to be related to the cost of energy, and how many miners are competing to secure the network. Any cost increase in mining is not tied to the number of coins whatsoever (or the number of transactions for that matter). As the mining reward drops, we could well see the hashrate drop, therefore the difficulty adjustment drops, and therefore the cost of mining decreases. We correlate the amount of bitcoin with a cost increase simply because demand tends to go up at the time of the halving.