Spend it like you got it
First let's think about how some problems can be solved with money. If you need more electricity capacity, or more help during a busy time, or more computing power, it's really easy to add capacity. You need more compute power, you can either buy more computers or just spend $2.15 in the cloud. If you need to dig a big hole, for a publicity stunt on Black Friday, you just pay someone to dig a big hole. It's not that hard.
This doesn't always work though, if you're building a new website, you probably can't buy your way to success. If a project like this falls behind it can be very difficult to catch back up. You can however track progress which I would say is at least a reasonable alternative. You can move development to another group or hire a new consultant if the old one isn't living up to expectations.
What if we need "more" security. How can we buy our way into more security for our organization? I'd start by asking the question can we show any actual value for our current security investment? If you stopped spending money on security tomorrow do you know what the results would be? If you stopped buying toilet paper for your company tomorrow you can probably understand what will happen (if you have a good facilities department I bet they already know the answer to this).
This is a huge problem in many organizations. If you don't know what would happen if you lowered or increased your security spending you're basically doing voodoo security. You can imagine many projects and processes as having a series of inputs that can be adjusted. Things like money, time, people, computers, the list could go on. You can control these variables and have direct outcomes on the project. More people could mean you can spend less money on contractors, more computers could mean less time spent on rendering or compiling. Ideally you have a way to find the optimal levels for each of these variables resulting in not only a high return on investment, but also happier workers as they can see the results of their efforts.
We can't do this with security today because security is too broad. We often don't know what would happen if we add more staff, or more technology.
So this brings us to why we can't spend our way to security. I would argue there are two real problems here. The first being "security" isn't a thing. We pretend security is an industry that means something but it's really a lot of smaller things we've clumped together in such a way that ensures we can only fail. I see security teams claim to own anything that has the word security attached to it. They claim ownership of projects and ideas, but then they don't actually take any actions because they're too busy or lack the skills to do the work. Just because you know how to do secure development doesn't automatically make you an expert at network security. If you're great at network security it doesn't mean you know anything about physical security. Security is a lot of little things, we have to start to understand what those are and how to push responsibility to respective groups. Having a special application security team that's not part of development doesn't work. You need all development teams doing things securely.
The second problem is we don't measure what we do. How many security teams tell IT they have to follow a giant list of security rules, but they have no idea what would happen if one or more of those rules were rolled back? Remember when everyone insisted we needed to use complex passwords? Now that's considered bad advice and we shouldn't make people change their passwords often. It's also a bad idea to insist they use a variety of special characters now. How many millions have been wasted on stupid password rules? The fact that we changed the rules without any fanfare means there was no actual science behind the rules in the first place. If we even tried to measure this I suspect we would have known YEARS ago that it was a terrible idea. Instead we just kept doing voodoo security. How many more of our rules do you think will end up being rolled back in the near future because they don't actually make sense?
If you're in charge of a security program the first bit of advice I'd give out is to look at everything you own and get rid of whatever you can. Your job isn't to do everything, figure out what you have to do, then do it well. One project well done is far better than 12 half finished. The next thing you need to do is figure out how much whatever you do costs, and how much benefit it creates. If you can't figure out the benefit, you can probably stop doing it today. If it costs more than it saves, you can stop that too. We must have a razor focus if we're to understand what our real problems are. Once we understand the problems we can start to solve them.