To what extent is investment banking luck?

Could a chat bot, like ChatGPT, be able to beat an industry professional with no prior relevant programming?

Investment banking is a generic term covering a range of banking activities. These include providing advice to companies on financing, takeovers, becoming listed on various stock exchanges etc. Investment banks may also carry out trading in financial securities on behalf of clients (normally large companies). The clients normally provide the instructions on what they want done and the clients bear the financial risks.  Investment banks may also invest some of the bank’s own money. This is often called ‘proprietary trading’. Proprietary trading is generally less common that it used to be, say ten or more years ago.  

If I understand your question correctly it is this ‘proprietary trading’ you are referring to. It is very similar to asset management but using the bank’s own money not that of clients.
There are many trading strategies. Many of them involved complex mathematical models with a range of risk equations. Most of the latter are aimed at reducing risk in case markets or event turn against the bank’s investments. In technical terms this is described as ‘risk hedging’. AI may well be built into these strategies. The AI used are not actually ‘chatbots’ but would, more likely be employed to construct the mathematical models used to consider, for example, risk. The latter can include interest rate, currency, market, liquidity, credit risks, and a few others, and consider how these risks may work together.

Things can and do go badly wrong. Recent examples include Credit Suisse bank and Archegos and Greensill. These disasters happened largely due to organisational and human ineptitude. Bad luck was not part of it. It is doubtful whether AI would have prevented them happening.