Most companies go through audits, and their investors will want to know where the money is. I don’t think you can say you’re buying Bitcoin when in reality you’re not buying anything. That would be worse than anything else. A lack of credibility can ruin any company. So these companies are probably actually buying it for real.

But why a company will do that, lying their bitcoin holdings, for what reasons. Microstrategy is too different for those companies just because they do such a thing, lure investments after they invest on bitcoin. It depends on its stocks, finance and business performance and so on. Look at their stock, its price is in ATH on this past weeks, means it performs better for many reasons.
Say microsoft stack bitcoin too, I wouldn't think investors will rally to go there just like your example on microstrategy, it will depend on the business performance and different matters too.

Yeah, that's a reasonable explanation why private companies cannot disclose their financial reports, as this could lead to other crimes that could be dangerous for the company.

But if a well known company lies by falsifying their bitcoin purchases, this could threaten the company's credibility.

And so far, no company has falsified their purchases.

I don't think companies would easily do that since the purpose of the investment is to hold BTC, not Bitcoin, unless their agreement is different.
The price of Bitcoin can be checked online publicly. If they are talking about Bitcoin, then you should know the price from time to time, and you should be able to calculate your shares from that company and how much interest or profit you get.

Also, we can verify if they bought bitcoin by making a sign message as proof of ownership. So it's impossible that they can fake buying Bitcoin this is not the same as when you are on the local market, where you can make a copy of the receipt with different info.

People will always find ways to uncover the truth, especially in this space where transparency is highly valued. If the claims are true, those involved will likely demand proof or clarity. But if they're not, it could be the beginning of the company's downfall, especially if it's a publicly traded business, stocks. Lying in this case would be extremely risky, considering the blockchain technology and data are publicly accessible. Any dishonesty could easily backfire, snd they will be considered as a fraud.

If they did choose to lie about their Bitcoin holdings they will be found out and it will only damage their business credibility and reputation and nobody wants that. I remember when even talking about Bitcoin in corporate America was completely frowned upon, now look how far we have come. Bitcoin is now king, cash has always been trash.

The blockchain is indeed public, transparent, but are centralized companies offering Bitcoin-related services as transparent? Take, for instance, centralized exchanges. Are those billions in daily Bitcoin/altcoin pairs backed 1:1 by real Bitcoin? I don't think so. Are those dozens of swap platforms declaring ample Bitcoin reserves transparent? No.

The Bitcoin market right now is dominated by centralized players, custodians, that aren't transparent. Some show proof of reserves that are shady at the very least. If we total all the paper Bitcoin, IOUs, hollow numbers, or whatever you call it, I'm sure it's way higher than what's actually circulating. This is certainly one of the reasons why despite the demand, the price remains relatively low.

All of the Bitcoin that aren't on-chain are fake Bitcoin. All Bitcoin that people keep in centralized platforms and custodial wallets are fake Bitcoin. Therefore, it's easy to fake Bitcoin, buying fake Bitcoin.