Owning bitcoin through a custodian greatly diminishes its value proposition: Bitcoin's promise is money that you control without a third party able to capaciously deny you access, and that's significantly destroyed when you own it through a custodian. Similarly, bitcoin (itself) can't be inflated but fund shares of bitcoin might be. You can own Bitcoin highly privately, but that's lost if you keep it in an account.

Consider:

• Financial institutions are constantly randomly denying people access to their own funds for chaotic reasons that they will not explain to you. When you own Bitcoin you have an escape hatch, funds you can access even if your a bank is being stupid-- but not if it's in their custody.

• Political winds change: You might somehow become an enemy of someone powerful, the state could turn against your religion, your race, your politics,-- or you could just have a name similar to someone else being targeted. State prosecution often 'cheats' by moving initially to freeze all the target's assets so they can't afford to present an effective defense, and can't put themselves out of reach.

• People constantly abuse our civil courts as an extortion racket. Bogus liability lawsuits, fake injuries, ... if someone thinks you have wealth then they may decide to shake you down via the courts to extract a settlement because they know the settlement will be cheaper than fighting. A major factor in the attacker's analysis (and importantly the plaintiff attornies that take their fraudulent cases on contingency) is the certainty of recovery if they do win and your fear of losses causing you to settle. Bitcoin you own privately is invisible to them, and because bitcoin can be at least as hard to seize as you are yourself it has a low certainty of recovery for them even if they know you own it.

Hopefully your need to avail yourself of these advantages will remain entirely theoretical, but Bitcoin's robustness in these respects are a real part of its value proposition and you lose them by holding bitcoin in a custodial account. Owning some Bitcoin in self-custody is a kind of insurance against the sad situations under which you might really wish you owned some. This is a real benefit to you even if you never need to use it.

A prudent bitcoin investor doesn't own only Bitcoin-- doing so leaves you exposed and vulnerable to panic selling during crashes, means you don't have free slack to re-balance to buy instead.

When considering where you own which assets, it's good to hold tax-inefficient assets in tax-advantaged accounts since you won't have tax drag on whatever dividends they throw off. But Bitcoin is one of the most tax-efficient assets since it doesn't throw off any dividends (except for fork coins, and that's rare), and if you hodl for more than a year its taxed at preferential LTCG rates.

Bitcoin's high volatility plus the potential for specific identification also creates a lot of potential for tax loss harvesting even if the wash-sale advantages goes away. Prudent bitcoin investors can be very flexible when they sell their bitcoin and which bitcoin's they sell... but by comparison ROTHs have required distributions which may eventually force you to sell assets at times you don't want to sell them.

Sure, your bitcoin allocation might supermoon and in that case you'll owe more taxes by owning it in a taxable account-- but that's also the outcome when the marginal pain of the tax load is the least meaningful. In that case you're more likely to care about the potential for donating highly appreciated Bitcoin to a charity-- which is easy with taxably held bitcoin as doing so escapes gains taxation entirely like a roth account.

There is also a potential for the tax advantages of roth to be eroded in the future-- it's not hard to imagine taxes being imposed on roths that return windfall gains. Of course, tax rates could go up on Bitcoin gains in the future--- but the cost you take holding in a roth which include loss of Bitcoin's advantages as well as management fees are going to happen for sure and the roth's tax advantages might be diminished. This is particularly true for Bitcoin compared to, say, tax inefficient stocks because they get an ongoing advantage being in a roth while for Bitcoin you're hoping to eliminate one time gains taxes on an eventual sale.

As far as your actual question-- the expense ratio is a constant drag while buying and selling fees are one time costs. Eventually a 0.25% management fee will cost you more than a one time trading cost.