Is it? You can register for 10 years at a time and then keep that topped up, as well as setup autopay pointed at a bank account with as many years of funds as you'd like. At some point the likely limiting factors shift to other things. Even the most reliable longest lasting registrars could in principle go out of business or get bought, but then again Google could decide to radically alter or discontinue services at some point too (as they indeed frequently have), or get broken up or who knows. 10 years is quite a while. And while nothing about business dealings is completely certain, someone paying for a domain a revenue generator with potential for more, so even if a registrar was acquired they'd have strong incentive to try to roll over existing accounts barring active objection.

I don't know your personal circumstances of course, different people may very reasonably make different calculations. But I have more trust in a quality registrar and my bank then in Google under the most likely scenarios where I'd still care (long comas aren't impossible to come out of, even multi-year, but chances of just partial recovery plummet after even a month or two let alone full recovery). I think Google being capricious or making a mistake is a bigger concern, if only because there is almost zero chance of recovering from it (basically have to know a well placed Googler or manage to go viral or be a big enough presence to get their attention). Domains and finance in contrast are both full of competition and portability.