Bitcoin is not like real items, which if the item very demand, then the supply is reduced, will make the pump price. bitcoin has been through a lot of things, but it doesn't yet have any other uses other than just for transactions and trading tools. halving the upcoming bitcoin does not guarantee that prices will rise. it's just that many predictions say it will be bullish. Well, I personally hope that the price of bitcoin will be bullish after halving. but can't be certain of that.
Bitcoin's main use is to preserve the purchasing power of your money, freedom in what you do with it, and when you actually want to purchase something. It is simply, a deflationary coin. It would be more correct to call it stable, but people have the wrong notion about that word. Bitcoin doesn't lose value overtime, but everybody else does. If Bitcoin were to peg its price to the others, it wouldn't be "stable" but inflationary. This is yet another reason why "stable" coins are a lie, if you peg to something that loses value overtime, you are losing value by design.
Bitcoin can in fact gain a little value because some coins stop circulating, because people lose their wallets, etc.
Most of the supply comes from coins that are already in the market. The percentage that comes from mining is smaller and smaller. It largely depends on the current bitcoin holders, just like gold, which most of it has been mined already.
As for the halving, in my opinion any uptrend may occur BEFORE the halving. After halving, could be a downtrend, or stabilization. It largely depends if this pre-halving uptrend comes or not, and how strong it is. The less strong, the less correction afterwards.